Patent Application
20230405588
The present disclosure relates generally to preparation of diagnostic samples and, more specifically, to apparatus, systems, and methods for preparing an output sample of bacteria of a target or desired concentration (or within acceptable error margins thereof) using ORP monitoring and aeration.
Infections caused by anti-infective resistant bacteria are a significant problem for healthcare professionals in hospitals, nursing homes, and other healthcare environments. Rapid detection of the susceptibility of such bacteria to antibiotics is crucial in order to prevent the spread of their resistance profiles. While new technologies (e.g., matrix-assisted laser desorptionlionization-time of flight mass spectrometry (MALDI-TOF MS), rapid polymerase chain reaction (rapid PCR), etc.) have been developed for identifying bacteria in samples such as positive blood cultures, the first step in most antibiotic susceptibility testing (AST) protocols still involves preparation of an output sample or inoculum having a concentration that matches a McFarland standard.
Existing methods and instruments used to prepare such output samples include costly, time-intensive (e.g., up to 24 hours), and labor-intensive microbial culturing techniques. However, those methods often require manual interpretation by skilled personnel and are prone to technical or clinician error. In addition, certain samples containing animal or human blood are often difficult to assess using prevailing optical techniques given the samples' opacity. Moreover, such optical techniques often require expensive equipment. Furthermore, while some methods discuss using a universal look-up table (LUT) to prepare an output sample, one drawback of methods that rely solely on a universal LUT is that the time to reach the target concentration is heavily influenced by the growth rate of the bacteria within the source sample. This means that the time it takes to prepare an output sample can vary greatly based on the bacteria within the source sample. This can make reliance on such methods impractical in busy laboratory settings.
As a result of the above limitations and restrictions, there is a need for improved apparatus, systems, and methods to quickly and effectively prepare an output sample of bacteria of a desired or target concentration for downstream testing.
Disclosed are various methods, devices, and systems for preparing an output sample of bacteria of a desired or target concentration. In one embodiment, a method of preparing an output sample of a desired or target concentration or within acceptable error margins (±0.5 log10) of the desired or target concentration can comprise: introducing an aliquot of a sample comprising the bacteria into a sample container, wherein the aliquot of the sample within the sample container is a contained sample in fluid communication with a reference sensor and an active sensor; incubating and aerating the contained sample, wherein the contained sample is aerated at a flow rate of between 7.0 microliter (μL) per second per milliliter (mL) of the contained sample and 10.0 μL per second per mL of the contained sample; monitoring a change in an oxidation reduction potential (ORP) of the contained sample using a reader electrically coupled to the reference sensor and the active sensor; and cooling the contained sample when a concentration of the bacteria in the contained sample is determined to have reached the desired or target concentration or within acceptable error margins thereof.
The method can comprise retrieving a species-agnostic look-up table (LUT) from a database, wherein the species-agnostic LUT comprises species-agnostic ORP change amounts associated with species-agnostic bacterial concentrations, wherein the species-agnostic LUT is generated from a plurality of constituent LUTs comprising ORP change amounts and bacterial concentrations measured using a plurality of reference bacterial samples incubated and aerated at a flow rate of between 7.0 μL per second per mL of each of the reference bacterial samples and 10.0 μL per second per mL of each of the reference bacterial samples.
The method can further comprise selecting one of the species-agnostic ORP change amounts as a threshold ORP change amount when the species-agnostic ORP change amount selected is associated with one of the species-agnostic bacterial concentrations equal to the desired or target concentration; and determining that the concentration of the bacteria in the contained sample has reached the desired or target concentration or within acceptable error margins thereof when the change in the ORP of the contained sample monitored by the reader reaches the threshold ORP change amount.
The species-agnostic LUT can be generated from at least three constituent LUTs including a first LUT, a second LUT, and a third LUT; wherein each of the first LUT, the second LUT, or the third LUT is either a species-specific LUT or a strain-specific LUT. The first LUT, the second LUT, and the third LUT can be generated using ORP measurements and bacterial concentration measurements made of a first reference bacterial sample, a second reference bacterial sample, and a third reference bacterial sample, respectively. The first reference bacterial sample can comprise a bacteria of a first species, the second reference bacterial sample can comprise a bacteria of a second species different from the first species, and the third reference bacterial sample can comprise a bacteria of a third species different from the second species and the first species.
Each of the strain-specific LUTs can be generated by: monitoring a change in the ORP of at least one reference bacterial sample over a period of time; periodically conducting optical density (OD) measurements of the at least one reference bacterial sample over the same period of time; converting results of the OD measurements to reference sample bacterial concentrations using a conversion factor; and associating the reference sample bacterial concentrations with the change in the ORP of the at least one reference bacterial sample.
The method can further comprise calculating a time-to-target concentration (ttarget) representing an amount of time required for the contained sample to reach the desired or target concentration (Ntarget) of bacteria using the following relationship:
wherein Ntarget is not included in the species-agnostic LUT and N1 is a species-agnostic bacterial concentration included in the species-agnostic LUT, wherein t1 represents a time required for the ORP of the contained sample to change by a species-agnostic ORP change amount (ΔORP) associated with N1 from the species-agnostic LUT, and wherein t1 is determined from real-time ORP monitoring conducted by the reader on the contained sample, and wherein tdoubling_average is an average bacterial doubling time. The method can also comprise determining that the concentration of the bacteria in the contained sample has reached the desired or target concentration or within acceptable error margins thereof when a time elapsed equals the time-to-target concentration.
The method can further comprise calculating a time-to-target concentration (ttarget) representing an amount of time required for the contained sample to reach the desired or target concentration (Ntarget) of bacteria using the following relationship:
wherein Ntarget and N1 are both included in the species-agnostic LUT, wherein Ntarget is greater than N1(Ntarget>N1), wherein t1 represents a time required for the ORP of the contained sample to change by a species-agnostic ORP change amount (ΔORP) associated with N1 from the species-agnostic LUT, and wherein t1 is determined from real-time ORP monitoring conducted by the reader on the contained sample, and wherein tdoubling_average is an average bacterial doubling time. The method can also comprise determining that the concentration of the bacteria in the contained sample has reached the desired or target concentration or within acceptable error margins thereof when a time elapsed equals the time-to-target concentration.
The sample can comprise at least one of a bodily fluid and a bacterial culture derived therefrom. The output sample can be prepared without any prior knowledge of a species of the bacteria in the contained sample or previously ascertaining a species of the bacteria in the contained sample. The bacteria within the contained sample can be a facultative anaerobe or a strict aerobe. Moreover, the bacteria within the contained sample can be a gram-negative bacteria. The desired or target concentration can be between 1.4×108 CFU/mL and 1.6×108 CFU/mL.
The method can further comprise diluting a source sample comprising the bacteria by a dilution factor between 1:10 and 1:100 to yield a diluted sample. The aliquot of the sample introduced into the sample container can be an aliquot of the diluted sample.
The reference sensor can comprise a reference electrode material and a wick in fluid communication with the contained sample such that least some of the contained sample within a chamber cavity of the sample container is drawn by the wick in a direction of the reference electrode material and the contained sample is in fluid contact with the reference electrode material. The active sensor can be coupled to at least part of a chamber lateral wall of the sample container. An active electrode material of the active sensor can face the chamber cavity such that the contained sample is in fluid contact with the active electrode material when the contained sample fills the chamber cavity. The ORP of the contained sample can be determined by the reader based on a potential difference measured between the active electrode material and the reference electrode material when the reference sensor and the active sensor are electrically coupled to the reader.
The contained sample can be incubated at an incubation temperature of between approximately 33° C. and 37° C. The contained sample can be aerated in accordance with an aeration cycle. The aeration cycle can comprise an aeration period followed by a non-aerated period. The aeration period can be longer than the non-aerated period. For example, the aeration period can be between about 7 minutes and 10 minutes and the non-aerated period can be between about 3 seconds and 10 seconds.
The contained sample can be aerated using a motorized piston pump. The motorized piston pump can be housed within the reader. Aerating the contained sample can further comprise pumping ambient air into the sample container through an opening defined along a base of the sample container.
Disclosed is also a system for preparing an output sample of bacteria of a desired or target concentration or within acceptable error margins (±0.5 log10) of the desired or target concentration of the desired or target concentration. The system can comprise a sensor apparatus comprising a container chamber configured to hold an aliquot of a sample comprising the bacteria, wherein the aliquot of the sample within the container chamber is a contained sample in fluid communication with a reference sensor and an active sensor; and a reader configured to receive the sensor apparatus, wherein the reader is also configured to incubate and aerate the contained sample when the sensor apparatus is positioned within the reader, wherein the contained sample is aerated at a flow rate of between 7.0 microliter (μL) per second per milliliter (mL) of the contained sample and 10.0 μL per second per mL of the contained sample. One or more processors of the reader are configured to monitor a change in an oxidation reduction potential (ORP) of the contained sample when the reader is electrically coupled to the reference sensor and the active sensor of the sensor apparatus, and cool the contained sample when a concentration of the bacteria in the contained sample is determined to have reached the desired or target concentration or within acceptable error margins thereof.
Variations of the apparatus, devices, systems, and methods disclosed herein are best understood from the detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings may not be to scale. On the contrary, the dimensions of the various features may be arbitrarily expanded or reduced for clarity and not all features may be visible or labeled in every drawing. The drawings are taken for illustrative purposes only and are not intended to define or limit the scope of the claims to that which is shown.
In some embodiments, the source sample can be obtained from a patient or subject. For example, the source sample can be obtained from a human patient or subject. In other embodiments, the source sample can be obtained from a non-human animal patient or subject.
In certain embodiments, the source sample can comprise a bodily fluid collected, extracted, or otherwise obtained from a patient or subject or a bacterial culture derived therefrom. More specifically, the bodily fluid can be at least one of blood, urine, serum, plasma, saliva, sputum, semen, breast milk, joint fluid, spinal fluid such as cerebrospinal fluid, wound material, mucus, fluid accompanying stool, vaginal secretions, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, and amniotic fluid.
In additional embodiments, the source sample can be a swab obtained from a patient or subject where the swab, or a portion thereof, is re-suspended in a liquid bacterial culture or nutrient medium. More specifically, the swab can be a wound swab, a rectal swab, or a vaginal swab.
In other embodiments, the source sample can be an environmental sample or a food/drink sample. For example, the source sample can comprise an environmental sample obtained from a stream, a river, a lake, an ocean, a contamination site, a quarantine zone, an emergency area, or a combination thereof. In other embodiments, the source sample can comprise a food sample obtained from a food preparation facility, a dining establishment, or a waste facility.
In all such embodiments, the source sample can comprise or contain bacteria. In certain embodiments, the source sample can be a bacterial culture derived from at least one of a patient sample, a biological sample, an environmental sample, and a food sample. For example, the source sample can be a bacterial culture or a re-suspended bacterial culture derived from a bodily fluid (or swab) obtained from a patient or subject.
As a more specific example, the source sample be a bacterial culture or a re-suspended bacterial culture derived from the blood of a patient or subject that has tested positive for bacterial growth. Such a source sample can also be referred to as a positive blood culture. For purposes of this disclosure, a positive blood culture (or PBC) is a bacterial culture derived from blood drawn from a patient or subject that has tested positive for bacterial growth. For example, a patient can show symptoms of sepsis (e.g., high fever, chills, etc.) and blood (e.g., 5 mL to 10 mL) can be drawn from the patient and transferred into a commercial blood culturing container or vessel that contain bacterial growth media (e.g., 30 mL to 40 mL of growth media). The blood culturing container or vessel can then be incubated at 35° C.±2° C. to allow the bacteria to proliferate. If the patient's blood is contaminated with bacteria, the bacteria will replicate within the container or vessel. A blood culturing system or apparatus can then be used to monitor for bacterial growth (such as by monitoring bacterial CO2 production within the container or vessel) and the system or apparatus can determine that the sample has tested “positive” for bacterial growth when a critical CO2 threshold has been met. Depending on the type of bacteria and the bacterial growth rate, the blood culture can turn positive between 7 hours and 3 days. Such a “positive blood culture” can then serve as the source sample.
As will be disclosed in more detail in the following sections, variations of the apparatus, devices, systems, and methods disclosed herein can be used to prepare an output sample or standardized inoculum of bacteria of a desired or target concentration (or within acceptable error margins thereof) from the source sample using ORP monitoring and aeration.
The sensor apparatus 100 can further comprise an active sensor 106 affixed, adhered, or otherwise coupled to at least part of the container chamber 102 and a reference sensor 108 integrated into or fabricated as part of the container cap 104.
The container chamber 102 can be made in part of an inert or non-conductive material. In some embodiments, the container chamber 102 can comprise or be made in part of a polymeric material, a ceramic material or glass, or a combination thereof. As a more specific example, the container chamber 102 can comprise or be made in part of polyvinyl chloride (PVC), poly(methyl methacrylate) (PMMA), polydimethylsiloxane (PDMS), or a combination thereof
As shown in
The active sensor 106 can be coupled to at least part of the chamber lateral wall 110 at a window opening 114 defined along the chamber lateral wall 110. The chamber lateral wall 110 can comprise a recessed portion 116 surrounding the window opening 114. The recessed portion 116 can be defined along an exterior side of the chamber lateral wall 110.
Regarding placement of the active sensor 106, the active sensor 106 can be configured such that no part of the active sensor 106 extends into the chamber cavity 112, as seen in
In some embodiments, a cavity volume of the chamber cavity 112 can be between about 0.8 mL and 1.2 mL. As a more specific example, the chamber cavity 112 can be about 1.0 mL. In other embodiments, the cavity volume of the chamber cavity 112 can be greater than 1.2 mL.
To adhere the active sensor 106 to the container chamber 102, a bead of adhesive 120 can be applied to an inner ledge 124 and/or a side border 126 of the recessed portion 116 and the active sensor 106 can then be pressed into the recessed portion 116 with an end-effector of a pick-and-place machine. The active sensor 106 can be pressed or otherwise urged into the recessed portion 116 until an exterior-facing surface of the active sensor 106 is flush with an exterior surface of the chamber lateral wall 110.
The adhesive 120 can then be cured to secure the active sensor 106 in place. In some embodiments, the adhesive 120 can be a medical-grade UV-cured adhesive. For example, the adhesive 120 can be the Dymax® 1405M-T-UR-SC adhesive (curable using LED light at a wavelength of approximately 405 nm). In other embodiments, the adhesive 120 can be any low-outgassing medical grade adhesive.
As previously discussed, the active sensor 106 can be made of a conductive substrate covered in part by an active electrode layer 118 or active electrode material. The active sensor 106 can be positioned such that the active electrode layer 118 faces the chamber cavity 112 to allow the sample within the chamber cavity 112 to be in fluid contact with the active electrode layer 118 through at least part of the chamber lateral wall 110 surrounding the window opening 114. In this embodiment, the active sensor 106 (including the active electrode layer 118) is positioned radially outward from an interior-facing or cavity-facing side of the chamber lateral wall 110 and the lateral sides 122 of the active sensor 106 are not exposed to the contained sample 113.
When the container chamber 102 is filled with the contained sample 113, the oxidation reduction potential (ORP) of the contained sample 113 can be measured or monitored by a reader 200 (see, e.g.,
In other embodiments, the pH of the contained sample 113 can also be measured or monitored by the reader 200. When the solution characteristic of the contained sample 113 measured or monitored is pH, the active electrode layer 118 can be a pH-sensitive material. For example, the pH-sensitive material can be or comprise any of silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), tantalum oxide/pentoxide (Ta2O5), hafnium dioxide (HfO2), iridium dioxide (IrO2), ruthenium dioxide (RuO2), zirconium dioxide (ZrO2), or a combination thereof.
Although not shown in the figures, it is contemplated by this disclosure that the sensor apparatus 100 can be designed such that both the pH and the ORP of the contained sample 113 are measured simultaneously. For example, the container chamber 102 of the sensor apparatus 100 can comprise multiple window openings 114 defined along the chamber lateral walls 110 of the container chamber 102. Each of these window openings 114 can then be covered by a different active sensor 106 (for example, one window opening 114 can be covered by an active sensor 106 having an active electrode layer 118 made of a redox-sensitive material and another window opening 114 can be covered by an active sensor 106 having an active electrode layer 118 made of a pH-sensitive material).
The sensor apparatus 100 can have an apparatus height. In some embodiments, the apparatus height can be between about 20.0 mm to about 50.0 mm. In other embodiments, the apparatus height can be between about 25.0 mm to about 35.0 mm. For example, the apparatus height can be about 31.3 mm.
The reference sensor 108 can also comprise a reference electrode material 132 and a wick or wicking component 134 in fluid communication with the chamber cavity 112. The reference conduit cavity 130 can house the wicking component 134. At least some of the contained sample 113 can be drawn up by the wicking component 134 in a direction of the reference electrode material 132.
The reference conduit 128 can be tapered such that a volume of the reference conduit cavity 130 tapers or narrows from a reference conduit proximal end 136 to a reference conduit distal end 138 (see
The wicking component 134 can extend through a length of the reference conduit cavity 130. In some embodiments, the wicking component 134 can fill up or occupy all of the space within the reference conduit cavity 130. In other embodiments, the wicking component 134 can partially fill up or partially occupy the space within the reference conduit cavity 130.
At least part of the wicking component 134 can be in fluid communication with the chamber cavity 112 of the container chamber 102 such that when the container chamber 102 is filled with the contained sample 113, at least some of the contained sample 113 in the container chamber 102 is drawn up, absorbed, or otherwise wicked by at least a portion of the wick distal end 142 in a direction of the wick proximal end 140. The wicking component 134 can be made of a polymeric material that draws up the contained sample 113 towards the reference electrode material 132 by capillary action.
In some embodiments, at least part of the wick distal end 142 can extend past the reference conduit distal end 138 such that the wick distal end 142 protrudes or extends into the chamber cavity 112 of the container chamber 102. In these embodiments, the wick distal end 142 can extend or protrude into the contained sample 113 when the container chamber 102 is filled by the contained sample 113.
In other embodiments, the wick distal end 142 is positioned proximal or above the reference conduit distal end 138 such that the wick distal end 142 does not protrude or extend into the chamber cavity 112 of the container chamber 102. In these embodiments, the wick distal end 142 can still be in fluid communication with the container chamber 102 and the contained sample 113 can still reach or contact the wick distal end 142 by being drawn up into the reference conduit 128 by capillary action or by perturbing or shaking the container chamber 102.
As previously discussed, the wicking component 134 can be made in part of a porous material. The wicking component 134 can be made in part of a material comprising pores sized between 15 μm to about 150 μm (e.g., about 50 μm). In some embodiments, the wicking component 134 can be made in part of a polymeric material. As a more specific example, the wicking component 134 can be made in part of a porous polymeric material comprising pores sized between 15 μm to about 150 μm. In one embodiment, the wicking component 134 can be made in part of high-density polyethylene (HDPE). For example, the wicking component 134 can be made in part of HDPE having pores sized about 50 μm. In other embodiments, the wicking component 134 can be made in part of natural fibers. For example, the wicking component 134 can be made in part of cellulose fibers, pulp, paper, cotton, or a combination thereof.
The wicking component 134 can also be treated by a surfactant such that at least a surface of the wicking component 134 is covered by the surfactant. In some embodiments, the wicking component 134 can be saturated by the surfactant or immersed in a solution comprising the surfactant prior to being introduced into the reference conduit cavity 130. The surfactant can be configured to increase a hydrophilicity of the wicking component 134 (i.e., to make a substantially hydrophobic surface of the wicking component 134 more hydrophilic). In some embodiments, the surfactant can be a fluorosurfactant. In other embodiments, the surfactant can be a non-ionic surfactant such as one or more Poloxamers. As a more specific example, the surfactant can comprise Pluronic® F-68.
In one embodiment, the reference conduit 128 can be substantially shaped as a conic or frustoconic having a reference conduit cavity 130 also substantially shaped as a conic or frustoconic. In other embodiments, the reference conduit 128 can be substantially shaped as an elongate pyramid having a polygonal-shaped base. For example, the reference conduit 128 can be substantially shaped as an elongate triangular pyramid, square pyramid, or a pentagonal pyramid. In additional embodiments, the reference conduit 128 can be substantially shaped as a cylinder having a substantially cylindrical-shaped reference conduit cavity 130. In these embodiments, the reference conduit 128 can have a tapered reference conduit distal end 138 (see, e.g.,
As shown in
The solution characteristic (e.g., ORP or pH) of the contained sample 113 can be determined based on a potential difference measured between the active sensor 106 and the reference sensor 108 when the reference sensor 108 and the active sensor 106 are electrically coupled to the reader 200. For example, the reference sensor 108 can provide a stable half-cell potential compared to the active sensor 106 when both the reference electrode material 132 and the active electrode layer 118 are in fluid contact with the contained sample 113 within the container chamber 102.
In some embodiments, the reference electrode material 132 can be an electrically-conductive ink applied or dispensed on the wick proximal end 140. The electrically-conductive ink applied or dispensed on the wick proximal end 140 can be hardened by curing. More specifically, the electrically-conductive ink can be a silver-silver chloride (Ag-AgCl) ink.
At least part of the reference electrode material 132 can be coupled to the wicking component 134. For example, the reference electrode material 132 can be a cured and hardened mass positioned at the wick proximal end 140. In certain embodiments, the reference electrode material 132 can be positioned in the middle of the container cap 104. In some embodiments, at least part of the reference electrode material 132 can protrude or extend beyond the container cap 104.
One advantage of the wicking component 134 disclosed herein is that the wicking component 134 can draw up the sample and the contained sample 113 can advance by capillary action through the pores of the wicking component 134 toward the reference electrode material 132. For example, the contained sample 113 can be wicked to the wick proximal end 140 where it makes fluid contact with the reference electrode material 132. When the reference electrode material 132 is made of a material such as silver-silver chloride (Ag-AgCl), the wicking component 134 can act as a barrier or hindrance to silver ions (Ag+) that would otherwise diffuse freely into the contained sample 113 within the container chamber 102. Such silver ions can be harmful to or otherwise affect the growth of the bacteria in the contained sample 113. The wicking component 134 can act as a barrier or hindrance to the harmful silver ions by slowing down or stalling the diffusion of such ions into the contained sample 113. The wicking component 134 having the dimensions and shape disclosed herein can be effective in slowing down or stalling the diffusion of such harmful ions.
When the reference sensor 108 is implemented as a container cap 104, the container cap 104 can have dimensions as defined by a cap width (or diameter) and a cap height. In some embodiments, the cap width can be between about 10.0 mm to about 20.0 mm. For example, the cap width can be about 15.7 mm. In some embodiments, the cap height can be between about 5.0 mm to about 20.0 mm. For example, the cap height can be about 10.5 mm. When the container cap 104 is fastened, affixed, or otherwise coupled to the container chamber 102, the sensor apparatus 100 can have an apparatus height as measured from a bottom of the container chamber 102 to a cap top 144 of the container cap 104.
The wicking component 134 can have a wick height as measured from the wick proximal end 142 to the wick distal end. In some embodiments, the wick height can be between about 10.0 mm to about 20.0 mm. More specifically, the wick height can be between about 14.0 mm to about 15.0 mm. For example, the wick height can be about 14.8 mm.
As illustrated in
In some embodiments, the reference electrode material 132 can have a reference electrode height and a reference electrode width. The reference electrode height can be between about 0.2 mm and 1.0 mm. For example, the reference electrode height can be about 0.4 mm. The reference electrode width can be between about 2.0 mm to about 5.0 mm. For example, the reference electrode width can be about 3.0 mm. One advantage of the reference sensor 108 disclosed herein is that the reference sensor 108 can act as a stable reference electrode or provide a stable reference potential for up to 10-hours of testing or operation.
The aeration port 146 can be covered by a first gas-permeable membrane 148. The aeration port 146 and the first gas-permeable membrane can be configured to allow a gas 150 to enter the container chamber 102.
In some embodiments, the gas 150 can be ambient air (e.g., the air in a laboratory, clinical setting, or testing facility). In other embodiments, the gas 150 can comprise a combination of pressurized oxygen, carbon dioxide, nitrogen, and argon. Aerating the sample can accelerate the growth of a bacterial population within the contained sample 113 by providing an oxygen rich environment within the container chamber 102.
In alternative embodiments not shown in the figures, the aeration port 146 can be defined along a cap top 144 of the container cap 104 and the gas 150 can be pumped into the container chamber 102 from the top of the container chamber 102.
The gas 150 (e.g., ambient air) can be pumped into the container chamber 102 by a motorized piston pump, syringe pump, or another type of pump/micropump device integrated within the reader 200. The gas 150 (e.g., ambient air) can be pumped or otherwise directed into the container chamber 102 through the aeration port 146 and the first gas-permeable membrane 148 at a flow rate of between 7.0 microliter (μL) per second per milliliter (mL) of the contained sample 113 and 10.0 μL per second per mL of the contained sample 113. As a more specific example, the gas 150 (e.g., ambient air) can be pumped or otherwise directed into the container chamber 102 through the aeration port 146 and the first gas-permeable membrane 148 at a flow rate of about 8.8 μL per second per mL of the contained sample 113. In some embodiments, the gas 150 (e.g., ambient air) can be pumped or otherwise directed into the container chamber 102 through the aeration port 146 and the first gas-permeable membrane 148 at specific duty cycles or intervals.
In certain embodiments, a second gas-permeable membrane 152 can cover at least part of an underside of the container cap 104. The second gas-permeable membrane 152 can allow any gas 150 pumped or otherwise introduced into the container chamber 102 to exit the container chamber 102 while also preventing any liquid within the container chamber 102 from spilling out of the container chamber 102.
In some embodiments, the first gas-permeable membrane 148 and the second gas-permeable membrane 152 can be made of the same material. The first gas-permeable membrane 148 and the second gas-permeable membrane 152 can be made of a hydrophobic gas-permeable film or thin-sheet. For example, the first gas-permeable membrane 148 and the second gas-permeable membrane 152 can both be made of or comprise polytetrafluoroethylene (PTFE).
As shown in
The container cap 104 can be made in part of a transparent or clear material or a transparent or clear non-conducting material. In other embodiments, the container cap 104 can be made in part of a translucent or see-through material. For example, at least part of the wicking component 134 can be visible through the sides of the container cap 104. This can allow a user or operator of the sensor apparatus 100 to observe the wicking of the contained sample 113 from the wick distal end 142 to the wick proximal end 140 when the container cap 104 is fastened to the container chamber 102 and ensure that at least some of the contained sample 113 is able to reach the reference electrode material 132 at the wick proximal end 140. In some embodiments, the container cap 104 can be made in part of a clear or transparent polymeric material, glass, or a combination thereof.
In some embodiments, the container chamber 102, the container cap 104, or a combination thereof can be made in part of an inert polymeric material. For example, the container chamber 102, the container cap 104, or a combination thereof can be made in part of at least one of polyoxymethylene, polyamide, polyethylene, acrylonitrile butadiene styrene, polycarbonate, polypropylene, or co-polymers or composites thereof. In other embodiments, the container chamber 102, the container cap 104, or a combination thereof can be made in part a glass material such as borosilicate glass or a ceramic material.
In some embodiments, the active sensor 106 can also be insert molded into part of the chamber lateral wall 110 when the container chamber 102 is made of a polymeric material. For example, the active sensor 106 can be insert-molded into the chamber lateral wall 110 while the container chamber 102 is being formed by injection molding.
When the active sensor 106 is inserted molded into part of the chamber lateral wall 110 of the container chamber 102, the active sensor 106 can have its lateral sides 122 encapsulated by the polymeric material used to make the chamber lateral wall 110.
For example, the active sensor 106 can be insert molded such that the active electrode layer 118 faces the chamber cavity 112 to allow the contained sample 113 within the chamber cavity 112 to be in fluid contact with the active electrode layer 118 through at least part of the chamber lateral wall 110 surrounding the window opening 114.
In some embodiments, the conductive layer 160 can be a gold layer. In other embodiments, the conductive layer 160 can be made of another type of conductive metal such as platinum, nickel, copper, or alloys or composites thereof.
Although not shown in the figures, it is contemplated by this disclosure that the active sensor 106 can be affixed or otherwise coupled to the chamber lateral wall 110 by focally melting (e.g., by ultrasonic welding) a portion of the chamber lateral wall 110 surrounding the window opening 114 (see, e.g.,
In some embodiments, the active sensor 106 can be substantially shaped as a flattened or truncated rectangular prism. In other embodiments, the active sensor 106 can be substantially disk-shaped or shaped as a flattened or truncated polygonal prism (e.g., a flattened or truncated pentagonal prism or hexagonal prism).
When the active sensor 106 is substantially shaped as a rectangular prism, the active sensor 106 can have a sensor length dimension, a sensor width dimension, and a sensor height dimension. In some embodiments, the sensor length dimension can be between about 100 μm and 6.0 mm, the sensor width dimension can be between about 100 μm and 6.0 mm, and the sensor height dimension can be between about 10 μm and 0.70 mm. For example, when the active sensor 106 is substantially shaped as a rectangular prism, the active sensor 106 can have a sensor length dimension of about 6.0 mm, a sensor width dimension of about 6.0 mm, and a sensor height dimension of about 0.61 mm.
In some embodiments, the active sensor 106 can have an active electrode layer 118 made of a noble metal. For example, the active electrode layer 118 can be made of platinum, gold, or a combination or composite thereof.
The active electrode layer 118 can be adhered to one side of a conductive substrate via an adhesion layer. The conductive substrate can be made of a conductive material such as stainless steel (SS). For example, the conductive substrate can be SS 316. In other embodiments, the conductive substrate can be made of aluminum, copper, or any combination or composite of aluminum, copper, or stainless steel.
In some embodiments, the adhesion layer can be a thin layer of chromium (Cr). Alternatively, the adhesion layer can be a thin layer of gold, nickel, titanium or tantalum. The adhesion layer can be disposed in between the conductive substrate and the active electrode layer 118.
In alternative embodiments, the active electrode layer 118 can be deposited directly onto one side of the conductive substrate without an adhesion layer.
The active electrode layer 118 can have an active electrode layer thickness of between about 50 nm and 500 nm (e.g., about 400 nm). The adhesion layer can have an adhesion layer thickness of between about 5 nm and 50 nm (e.g., about 20 nm). A ratio of the adhesion layer thickness to the active electrode layer thickness can be between about 1:10 and 1:20.
The conductive substrate can have a substrate layer thickness. The substrate layer thickness can be between about 10 μm and 0.70 mm (e.g., about 0.61 mm).
In other embodiments, the active electrode layer 118 can be made of a metal oxide. For example, the active electrode layer 118 can be made of tantalum pentoxide (Ta2O5). In other embodiments, the active electrode layer 118 can be made of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), titanium dioxide (TiO2), hafnium dioxide (HfO2), iridium dioxide (IrO2), ruthenium dioxide (RuO2), zirconium dioxide (ZrO2), or a combination or composite thereof. In these embodiments, the conductive substrate can be made of a conductive material such as stainless steel (SS). For example, the conductive material can be SS 316. The conductive substrate can also be made of aluminum, copper, or any combination or composite of aluminum, copper, or stainless steel.
The deposited layers can be selected to achieve a certain desired sensitivity or specificity towards a particular analyte. Other surface modification techniques such as self-assembled monolayers (SAMs), bio-functionalization with antibodies, binding antibody fragments, binding aptamers, binding DNA, and plasma treatments can also be employed to alter the surface properties of the deposited layers and thereby tune their specificity and sensitivity.
In certain embodiments, the active sensor 106 can leverage the scale and efficiency of printed circuit board (PCB) manufacturing techniques. For example, the active sensor 106 can be made of a non-conductive PCB substrate covered in part by an active electrode layer 118. In some embodiments, the non-conductive PCB substrate can be made of polyimide. In other embodiments, the non-conductive PCB substrate can be made of a glass-reinforced epoxy laminate material such as an FR-4 composite material. In certain embodiments, the PCB substrate can be a flexible PCB material.
In some embodiments, the active electrode layer 118 can be made of a noble metal. For example, the active electrode layer 118 can be made of platinum, gold, or a combination or composite thereof. The platinum or gold can be electrodeposited or sputter deposited on the PCB substrate.
The active electrode layer 118 can have an active electrode layer thickness of at least 50 nm. In certain embodiments, the active electrode layer 118 can have an active electrode layer thickness of at least 400 nm. When the active electrode layer 118 is made of platinum, the active sensor 106 can be used for measuring or monitoring the ORP of a sample.
In an alternative embodiment, a platinum layer deposited on the non-conductive PCB substrate can be modified with a surface modification technique to turn the platinum layer into a pH-sensitive layer. For example, an oxygen plasma treatment can be used to oxidize the platinum layer to create a platinum oxide (PtO2) layer. The platinum oxide layer thus formed can respond to hydrogen ions and be used as a pH-sensitive layer. In this embodiment, the active sensor 106 can be used to measure or monitor the pH of a sample.
The PCB substrate can be patterned with conductive contacts or a conductive layer 160 on a side of the substrate opposite the active electrode layer 118. In some embodiments, the conductive layer 160 can be a gold layer. In other embodiments, the conductive layer 160 can be made of another type of conductive metal such as platinum, nickel, copper, or alloys or composites thereof.
In some embodiments, the active electrode layer 118 can be electrically coupled to the conductive layer 160 by one or more conductive vias. In one embodiment, the conductive vias can be made in part of copper or a copper alloy. In other embodiments, the conductive vias can be made of another type of conductive metal such as gold.
In some embodiments, each active sensor 106 can have at least one conductive via positioned in a center of the sensor package. In other embodiments, the conductive via can be positioned near a periphery or edge of the sensor package.
The conductive vias can be formed by electroplating, deposition, or a combination thereof. Moreover, additional features or patterns can be formed on the PCB substrate using standard PCB etching processes.
The reader 200 can comprise a reader housing 202 configured to house certain functional components of the reader 200 including a main controller 208 (see, e.g.,
A lid 206 or cover of the reader 200 can be opened or lifted up to reveal a container receiving space configured to accommodate or receive the sensor apparatus 100 (the container receiving space is the space occupied by the sensor apparatus 100 in
In some embodiments, the heating block 220 can be made in part of aluminum. In other embodiments, the heating block 220 can be made in part of another type of heat conducting metallic material.
The sensor apparatus 100 can be heated to an incubation temperature of between about 30° C. and 40° C. (e.g., about 35° C.±2° C.). The sensor apparatus 100 can be incubated for an incubation period. The incubation period can range from 15 minutes to over 2 hours. The incubation period can be adjusted based on the type of bacteria suspected in the source sample.
The thermal control module 212 can also be used to cool the contained sample 113 to a cooling temperature when the solution characteristic (e.g., the ORP or pH) of the contained sample 113 changes by a threshold amount indicating that the bacteria within the contained sample 113 has reached a desired or target concentration or has reached a desired or target concentration level within acceptable error margins thereof. In other embodiments, the thermal control module 212 can be used to cool the contained sample 113 to a cooling temperature when an elapsed time reaches certain time limits or time thresholds. In some embodiments, the thermal control module 212 can cool the contained sample 113 within the sensor apparatus 100 at a cooling temperature between about 4° C. and 25° C.
When the bacteria within the contained sample 113 has reached the desired or target concentration (or within acceptable error margins thereof), the contained sample 113 within the sensor apparatus 100 can be considered an output sample ready for further downstream testing (e.g., antibiotic susceptibility testing). In certain embodiments, the reader 200 can comprise an auditory component (e.g., a speaker) and the auditory component can generate an auditory signal (i.e., sound an alarm) to notify a user or laboratory technician that the output sample has been prepared and is ready for further downstream testing.
In some embodiments, the thermal control module 212 can be controlled by the main controller 208 of the reader 200. In other embodiments, the thermal control module 212 can be controlled by another controller or module within the reader 200 or by the signal readout control unit 210.
In some embodiments, a nutrient solution or stimulus solution can be introduced into the container chamber 102 before the sensor apparatus 100 is incubated. For example, the nutrient solution can be a solution containing bacto-tryptone, yeast extract, beef extract, cation-adjusted Mueller Hinton Broth (CAMHB), starch, an acid hydrolysate of casein, calcium chloride, magnesium chloride, sodium chloride, blood or lysed blood including lysed horse blood (LHB), a CAMHB-LHB mixture, glucose, or a combination thereof. The nutrient solution can be used to counteract the buffering effects of ions or substances present in the sample when the sample is composed of a bodily fluid.
The aeration control module 214 can be configured to aerate the contained sample 113 within the container chamber 102 by pumping a gas 150 (e.g., ambient air, see
As previously discussed, a container cap 104 (serving as part of the reference sensor 108) of the sensor apparatus 100 can be fastened or coupled to the container chamber 102 by a threaded connection 154 that allows part of an airflow pathway 156 to be created in between the threads of the container cap 104 and the threads of the container chamber 102. After the gas 150 (e.g., ambient air) enters the aeration port 146 through the first gas-permeable membrane 148 into the container chamber 102, the gas first aerates the contained sample 113 and then exits the container chamber 102 through the second gas-permeable membrane 152 and the air gaps 158 defined in between the threads of the container cap 104 and the container chamber 102.
In some embodiments, aeration control module 214 can comprise one or more filters (e.g., inline filters, conduit filters, pipe filters, and/or hose filters) for filtering the ambient air drawn into the aeration control module 214. In additional embodiments, the gas delivery conduit 224 can comprise an inline filter configured to filter the ambient air and remove particulates from the ambient air before the ambient air reaches the sensor apparatus 100 and/or the gas nozzle 222.
As shown in
In some embodiments, the gas 150 can be ambient air (e.g., the air in a laboratory, clinical setting, or testing facility). In other embodiments, the gas 150 can comprise a combination of pressurized oxygen, carbon dioxide, nitrogen, and argon. Aerating the sample can accelerate the growth of a microbial population within the sample by providing an oxygen rich environment within the container chamber 102.
Aerating the contained sample 113 can enhance a growth rate of the bacteria in the contained sample 113 within the sensor apparatus 100 by increasing the supply of oxygen to such bacteria. Moreover, aerating the contained sample 113 can also enable detachment of the bacteria from the interior walls of the container chamber 102 so as to inhibit biofilm formation.
Although aeration is important for enhancing the growth rate of bacteria within the sensor apparatus 100, the applicants have also discovered that too much aeration or aerating the contained sample 113 at higher flow rates can have certain detrimental effects on the ORP signal monitored by the reader 200. For example, while aerating the contained sample 113 can, in most cases, increase the growth rate of bacteria (especially aerobic bacteria) within the contained sample 113, too much aeration can suppress the ORP signal and introduce errors into the ORP measurements. Moreover, too much aeration can also cause any changes in ORP values (ΔORP) to be too small to be of any value in differentiating between different bacterial concentration levels.
Furthermore, too little aeration or aerating the contained sample 113 at lower flow rates can cause the contained sample 113 to become stagnant and can cause sample preparation times to be sub-optimal or slower.
Therefore, the contained sample 113 within the sensor apparatus 100 should be aerated at a flow rate within an optimal range that avoids the aforementioned shortcomings. One such range discovered by the applicants is a flow rate between 7.0 microliter (μL) per second per milliliter (mL) of the contained sample 113 and 10.0 μL per second per mL of the contained sample 113. More specifically, the contained sample 113 can be aerated at a flow rate of about 8.8 (±0.9) μL per second per mL of the contained sample 113.
In some embodiments, the contained sample 113 can be aerated using a motorized piston pump. The motorized piston pump can be housed or contained within the reader 200. In certain embodiments, the motorized piston pump can be housed or contained completely within the reader 200. For example, the motorized piston pump can be housed or contained within the aeration control module 214.
The motorized piston pump can be actuated by one or more stepper motors and lead screw drives. The motorized piston pump can be controlled by a dedicated controller, the main controller 208, or a combination thereof. As a more specific example, the motorized piston pump can be a modified version of the Cavro® Pulssar piston pump. In other embodiments, the contained sample 113 can be aerated using a syringe pump or a motorized syringe pump.
In some embodiments, the contained sample 113 within the sensor apparatus 100 can be aerated in accordance with an aeration cycle. The aeration cycle can include an aeration period followed by a non-aerated period where no gas or ambient air is pumped into the container chamber 102. In certain embodiments, the aeration period can be longer than the non-aerated period. For example, the aeration period can be between about 7 minutes and 10 minutes and the non-aerated period can be between about 3 seconds and 10 seconds.
One technical problem faced by the applications is that motorized piston pumps often require that the pump piston to be drawn back or re-homed once the pump piston has reached the distal end of the pump chamber or barrel. One technical solution discovered and developed by the applicants to address this technical problem is to use the non-aerated period to draw back or re-home the pump piston.
In some embodiments, the aeration control module 214 can be controlled by the main controller 208 (see, e.g.,
In some embodiments, the reference electrode contact 216 and the active electrode contact 218 can comprise one or more conductive pogo or spring-loaded pins, conductive leaf contacts, or a combination thereof. More specifically, the conductive pogo pins or leaf contacts can be made of copper, nickel, stainless steel, or alloys thereof.
The reference electrode contact 216 and the active electrode contact 218 can be electrically coupled to a signal readout control unit 210. The signal readout control unit 210 can comprise one or more processors, chipsets, or chip modules programmed to convert and read signals obtained from the active sensor 106 and the reference sensor 108 of the sensor apparatus 100. For example, the signal readout control unit 210 can determine an ORP of the contained sample 113 within the sensor apparatus 100 based on a potential difference measured between the active electrode layer 118 and the reference electrode material 132.
The active electrode layer 118 is chosen so that it easily interacts with oxidized/reduced molecules in the contained sample 113 (i.e., no activation barrier or additional energy needs to be provided). The active electrode layer 118 is inert (e.g., a platinum or gold layer/material) in that it does not participate in any redox reactions but it is redox-sensitive or redox-active in the sense that it serves as both a source and sink of electrons (responding to the redox state of the contained sample 113). The active electrode layer 118 is considered inert because the process of transferring electrons does not change the material of the electrode or its oxidation state. The electrons are spontaneously transferred to the active electrode layer 118 from the contained sample 113 and from the active electrode layer 118 to the contained sample 113. A higher concentration of oxidized molecules (positive ORP value) implies a higher tendency for these molecules to accept electrons from the active electrode layer 118, whereas a higher concentration of reduced molecules (negative ORP value) implies a higher tendency for the molecules to give up electrons to the active electrode layer 118. Therefore, one either ends up with a loss of electrons on the active electrode layer 118, which results in a positive ORP value or one ends up with an excess of electrons on the active electrode layer 118, which results in a negative ORP value.
Different redox-active species are generated during bacterial metabolism and growth. That is, bacterial growth and/or metabolic processes involve the conversion of oxidized molecules into reduced ones. As the amount of bacteria in the contained sample 113 increases, the concentration of reduced molecules/compounds increases. This, in turn, causes the ORP of the contained sample 113 to decrease.
As a more specific example, the amount of electron donors from Table 1 below (e.g., the amount of energy carriers such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2)) in the contained sample 113 can change due to the growth of bacteria in the contained sample 113.
2 Pyruvate + 2e−
6 CO2 + 24e−
2H+ + 2e−
NAD+ +2e−
GSSG + 2e−
SO42− + 8e−
FAD + 2H+ + 2e−
Pyruvate + 2e−
Fumarate + 2e−
Cyt b (ox) + e−
Ubiquinone + 2e−
Cyt c (ox) + e−
Cyt a (ox) + e−
NO3
NO2
MnO2 + 2e−
NO3− + 5e−
Fe3+ + 1e−
½ O2 + 2H+ + 2e−
The reference electrode material 132 is chosen so that it maintains a constant potential through the measurement/monitoring and is not affected by or take part in any of the redox changes occurring in the contained sample 113.
The potential difference measured between the active electrode layer 118 and the reference electrode material 132 is measured in an open-circuit configuration. That is, no current flows through the system and the potential difference is measured using a very high impedance voltage measurement circuit or high impedance voltmeter integrated into the reader 200 (e.g., integrated into the signal readout control unit 210).
The ORP of the contained sample 113 is measured without any added reporter molecules or added redox mediators.
The bacteria 302 can be of a genera selected from the group consisting of: Acinetobacter, Acetobacter, Actinomyces, Aerococcus, Aeromonas, Agrobacterium, Anaplasma, Azorhizobium, Azotobacter, Bacillus, Bacteroides, Bartonella, Bordetella, Borrelia, Brucella, Burkholderia, Calymmatobacterium, Campylobacter, Chlamydia, Chlamydophila, Citrobacter, Clostridium, Corynebacterium, Coxiella, Ehrlichia, Enterobacter, Enterococcus, Escherichia, Francisella, Fusobacterium, Gardnerella, Haemophilus, Helicobacter, Klebsiella, Lactobacillus, Legionella, Listeria, Methanobacterium, Microbacterium, Micrococcus, Morganella, Moraxella, Mycobacterium, Mycoplasma, Neisseria, Pandoraea, Pasteurella, Peptostreptococcus, Porphyromonas, Prevotella, Proteus, Providencia, Pseudomonas, Ralstonia, Raoultella, Rhizobium, Rickettsia, Rochalimaea, Rothia, Salmonella, Serratia, Shewanella, Shigella, Spirillum, Staphylococcus, Strenotrophomonas, Streptococcus, Streptomyces, Treponema, Vibrio, Wolbachia, and Yersinia.
More specifically, the bacteria 302 can be of a species selected from the group consisting of: Acinetobacter baumannii, Actinobacillus spp., Actinomycetes, Actinomyces spp. (including but not limited to Actinomyces israelii and Actinomyces naeslundii), Aeromonas spp. (including but not limited to Aeromonas hydrophila, Aeromonas veronii biovar sobria (Aeromonas sobria), and Aeromonas caviae), Anaplasma phagocytophilum, Alcaligenes xylosoxidans, Actinobacillus actinomycetemcomitans, Bacillus spp. (including but not limited to Bacillus anthracis, Bacillus cereus, Bacillus subtilis, Bacillus thuringiensis, and Bacillus stearothermophilus), Bacteroides spp. (including but not limited to Bacteroides fragilis), Bartonella spp. (including but not limited to Bartonella bacilliformis and Bartonella henselae, Bifidobacterium spp., Bordetella spp. (including but not limited to Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica), Borrelia spp. (including but not limited to Borrelia recurrentis, and Borrelia burgdorferi), Brucella spp. (including but not limited to Brucella abortus, Brucella canis, Brucella melintensis and Brucella suis), Burkholderia spp. (including but not limited to Burkholderia pseudomallei and Burkholderia cepacia), Campylobacter spp. (including but not limited to Campylobacter jejuni, Campylobacter coli, Campylobacter lari and Campylobacter fetus), Capnocytophaga spp., Cardiobacterium hominis, Chlamydia trachomatis, Chlamydophila pneumoniae, Chlamydophila psittaci, Citrobacter spp., Coxiella burnetii, Corynebacterium spp. (including but not limited to, Corynebacterium diphtheriae, Corynebacterium jeikeum and Corynebacterium), Clostridium spp. (including but not limited to Clostridium perfringens, Clostridium difficile, Clostridium botulinum and Clostridium tetani), Eikenella corrodens, Enterobacter spp. (including but not limited to Enterobacter aerogenes, Enterobacter agglomerans, Enterobacter cloacae and Escherichia coli, including opportunistic Escherichia coli, including but not limited to enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli and uropathogenic E. coli), Enterococcus spp. (including but not limited to Enterococcus faecalis and Enterococcus faecium), Ehrlichia spp. (including but not limited to Ehrlichia chafeensia and Ehrlichia canis), Erysipelothrix rhusiopathiae, Eubacterium spp., Francisella tularensis, Fusobacterium nucleatum, Gardnerella vaginalis, Gemella morbillorum, Haemophilus spp. (including but not limited to Haemophilus influenzae, Haemophilus ducreyi, Haemophilus aegyptius, Haemophilus parainfluenzae, Haemophilus haemolyticus and Haemophilus parahaemolyticus, Helicobacter spp. (including but not limited to Helicobacter pylori, Helicobacter cinaedi and Helicobacter fennelliae), Kingella kingii, Klebsiella spp. (including but not limited to Klebsiella pneumoniae, Klebsiella granulomatis and Klebsiella oxytoca), Lactobacillus spp., Listeria monocytogenes, Leptospira interrogans, Legionella pneumophila, Leptospira interrogans, Peptostreptococcus spp., Moraxella catarrhalis, Morganella spp., Mobiluncus spp., Micrococcus spp., Mycobacterium spp. (including but not limited to Mycobacterium leprae, Mycobacterium tuberculosis, Mycobacterium intracellulare, Mycobacterium avium, Mycobacterium bovis, and Mycobacterium marinum), Mycoplasm spp. (including but not limited to Mycoplasma pneumoniae, Mycoplasma hominis, and Mycoplasma genitalium), Nocardia spp. (including but not limited to Nocardia asteroides, Nocardia cyriacigeorgica and Nocardia brasiliensis), Neisseria spp. (including but not limited to Neisseria gonorrhoeae and Neisseria meningitidis), Pasteurella multocida, Plesiomonas shigelloides, Prevotella spp., Porphyromonas spp., Prevotella melaninogenica, Proteus spp. (including but not limited to Proteus vulgaris and Proteus mirabilis), Providencia spp. (including but not limited to Providencia alcalifaciens, Providencia rettgeri and Providencia stuartii), Pseudomonas aeruginosa, Propionibacterium acnes, Rhodococcus equi, Rickettsia spp. (including but not limited to Rickettsia rickettsii, Rickettsia akari and Rickettsia prowazekii, Orientia tsutsugamushi (formerly: Rickettsia tsutsugamushi) and Rickettsia typhi), Rhodococcus spp., Stenotrophomonas maltophilia, Salmonella spp. (including but not limited to Salmonella enterica, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Salmonella cholerasuis and Salmonella typhimurium), Serratia spp. (including but not limited to Serratia marcesans and Serratia liquifaciens), Shigella spp. (including but not limited to Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei), Staphylococcus spp. (including but not limited to Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hemolyticus, Staphylococcus saprophyticus), Streptococcus spp. (including but not limited to Streptococcus pneumoniae (for example chloramphenicol-resistant serotype 4 Streptococcus pneumoniae, spectinomycin-resistant serotype 6B Streptococcus pneumoniae, streptomycin-resistant serotype 9V Streptococcus pneumoniae, erythromycin-resistant serotype 14 Streptococcus pneumoniae, optochin-resistant serotype 14 Streptococcus pneumoniae, rifampicin-resistant serotype 18C Streptococcus pneumoniae, tetracycline-resistant serotype 19F Streptococcus pneumoniae, penicillin-resistant serotype 19F Streptococcus pneumoniae, and trimethoprim-resistant serotype 23F Streptococcus pneumoniae, chloramphenicol-resistant serotype 4 Streptococcus pneumoniae, spectinomycin-resistant serotype 6B Streptococcus pneumoniae, streptomycin-resistant serotype 9V Streptococcus pneumoniae, optochin-resistant serotype 14 Streptococcus pneumoniae, rifampicin-resistant serotype 18C Streptococcus pneumoniae, penicillin-resistant serotype 19F Streptococcus pneumoniae, or trimethoprim-resistant serotype 23F Streptococcus pneumoniae), Streptococcus agalactiae, Streptococcus mutans, Streptococcus pyogenes, Group A Streptococci, Streptococcus pyogenes, Group B Streptococci, Streptococcus agalactiae, Group C Streptococci, Streptococcus anginosus, Streptococcus equismilis, Group D Streptococci, Streptococcus bovis, Group F Streptococci, Streptococcus anginosus, and Group G Streptococci), Spirillum minus, Streptobacillus moniliformi, Treponema spp. (including but not limited to Treponema carateum, Treponema petenue, Treponema pallidum and Treponema endemicum, Tropheryma whippelii, Ureaplasma urealyticum, Veillonella spp., Vibrio spp. (including but not limited to Vibrio cholerae, Vibrio parahemolyticus, Vibrio vulnificus, Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio alginolyticus, Vibrio mimicus, Vibrio hollisae, Vibrio fluvialis, Vibrio metchnikovii, Vibrio damsela and Vibrio furnisii), Xanthomonas maltophilia, and Yersinia spp. (including but not limited to Yersinia enterocolitica, Yersinia pestis, and Yersinia pseudotuberculosis).
The method 300 can be used to prepare an output sample of bacteria 302 of a desired or target concentration (or within acceptable error margins thereof) when the bacteria 302 is an obligate or strict aerobe. The method 300 can also be used to prepare an output sample of bacteria 302 of a desired or target concentration (or within acceptable error margins thereof) when the bacteria 302 is a facultative anaerobe. The method 300 can further be used to prepare an output sample of bacteria 302 of a desired or target concentration (or within acceptable error margins thereof) when the bacteria 302 is a gram-negative bacteria.
One unexpected discovery made by the applicants is that the method and system disclosed herein works especially well to prepare an output sample of a desired or target concentration (or within acceptable error margins thereof) from a source sample comprising bacteria that are classified or considered as obligate or strict aerobes. For example, for certain species of obligate or strict aerobes, such as Acinetobacter baumannii (ABa) and Pseudomonas aeruginosa (PAe), the methods disclosed herein have been shown to significantly decrease sample preparation times for such obligate or strict aerobes compared to methods that do not use aeration.
Another unexpected discovery made by the applicants is that the method and system disclosed herein also works well to prepare an output sample of a desired or target concentration (or within acceptable error margins thereof) from a source sample comprising bacteria that are classified or considered as facultative anaerobes such as Escherichia coli (ECo), Serratia marcescens (SMa), and Proteus mirabilis (PMi). For example, for certain species of facultative anaerobes, the methods disclosed herein have been shown to decrease sample preparation times for such facultative anaerobes compared to methods that do not use aeration.
Yet another unexpected discovery made by the applicants is that the method and system disclosed herein works well to prepare an output sample of a desired or target concentration (or within acceptable error margins thereof) from a source sample comprising gram-negative bacteria that are classified or considered as facultative anaerobes or obligate/strict aerobes. For example, the applicants discovered that the method disclosed herein works especially well for preparing an output sample of a desired or target concentration, or within acceptable error margins thereof, from a source sample comprising the following species of gram-negative bacteria: ECo, SMa, PMi, Proteous vulgaris (PVu), ABa, PAe, Klebsiella pneumoniae (KPn), Enterobacter cloacae (ECl), Klebsiella oxytoca (KOx), Klebsiella aerogenes (KAe), Citrobacter braakii (CBr), Citrobacter freundii (CFr), and Citrobacter koseri (CKo).
In alternative embodiments, the method 300, devices, and system 301 disclosed herein can also be used to prepare an output sample of mold or fungi of a desired or target concentration (or within acceptable error margins thereof). The fungi can be of a genera selected from the group consisting of: Candida and Cryptococcus. More specifically, the fungi can be of a species selected from the group consisting of: Candida spp. (including but not limited to Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei), Aspergillus spp. (including but not limited to Aspergillus fumigatus, Aspergillus flavus, Aspergillus clavatus), Cryptococcous spp. (including but not limited to Cryptococcus neoformans, Cryptococcus gattii, Cryptococcus laurentii, and Cryptococcus albidus), Fusarium spp. (including but not limited to Fusarium oxysporum, Fusarium solani, Fusarium verticillioides, and Fusarium proliferatum), Rhizopus oryzae, Penicillium marneffei, Coccidiodes immitis, and Blastomyces dermatitidis.
The method 300 can comprise diluting an aliquot of a source sample comprising bacteria 302 by a dilution factor to yield a diluted sample 304 in step 300A. As previously discussed, the source sample can be obtained from a patient or subject. In some embodiments, the source sample can be obtained from a human patient or subject. In other embodiments, the source sample can be obtained from a non-human animal patient or subject. In certain embodiments, the source sample can comprise a bodily fluid collected, extracted, or otherwise obtained from a patient or subject or a bacterial culture derived therefrom. The bodily fluid can be at least one of blood, urine, serum, plasma, saliva, sputum, semen, breast milk, joint fluid, spinal fluid such as cerebrospinal fluid, wound material, mucus, fluid accompanying stool, vaginal secretions, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, and amniotic fluid. For example, the source sample be a bacterial culture or a re-suspended bacterial culture derived from a bodily fluid (or swab) obtained from a patient or subject that has tested positive for bacterial growth. More specifically, the source sample can be a positive blood culture (PBC).
In additional embodiments not shown in
The aliquot of the source sample can be diluted using a dilutive solution 306. The dilutive solution 306 can comprise growth media (e.g., bacteria growth media) or a growth inducer. In some embodiment, the dilutive solution 306 can be a solution containing a cation-adjusted Mueller Hinton Broth (CAMHB), a glucose supplemented Mueller Hinton broth (MHG), a CAMHB-LHB mix, bacto-tryptone, tryptic soy digest, yeast extract, beef extract, starch, acid hydrolysate of casein, calcium chloride, magnesium chloride, sodium chloride, blood or lysed blood including lysed horse blood (LHB), glucose or other carbohydrates, or a combination thereof. The growth inducer can comprise a carbon-based inducer, a nitrogen-based inducer, a mineral, a trace element, a biological growth factor, or any combination thereof. For example, the growth inducer can include but is not limited to a carbohydrate such as glucose or starches, ammonia, magnesium, amino acids, casamino acids, vitamins, peptides, blood, or a combination thereof. In one example embodiment, the dilutive solution 306 can comprise tryptone, yeast extract, sodium chloride, starch, water, and glucose.
The dilution factor can be between about 1:1 to 1:100 or 1:1 to 1:1000. In some embodiments, the dilution factor can be between about 1:10 to 1:100. More specifically, the dilution factor can be between about 1:10 and 1:50. For example, the dilution factor can be about 1:30 when the source sample is a positive blood culture. As a more specific example, a 30 μL source sample can be diluted into 1 mL of the dilutive solution 306.
Although
The method 300 can also comprise introducing an aliquot of the diluted sample 304 comprising the bacteria 302 into a container chamber 102 of the sensor apparatus 100 in step 300B. The amount of diluted sample 304 introduced can depend on a volume of the chamber cavity 112 of the container chamber 102 (see, e.g.,
The aliquot of the diluted sample 304 within the container chamber 102 can be in fluid communication with both an active sensor 106 and a reference sensor 108 of the sensor apparatus 100. For purposes of this disclosure, the aliquot of the diluted sample 304 within the container chamber 102 will be referred to as the contained sample 113.
As previously discussed, the active sensor 106 can be coupled to at least part of a chamber lateral wall 110 of the container chamber 102. The active sensor 106 can also comprise an active electrode material or active electrode layer 118 that faces the chamber cavity 112 such that the contained sample 113 is in fluid contact with the active electrode material or active electrode layer 118 when the contained sample 113 fills the chamber cavity 112 of the container chamber 102.
Also, as previously discussed, the reference sensor 108 can comprise a reference electrode material 132 and a wick or wicking component 134 in fluid communication with the chamber cavity 112 of the container chamber 102. When the container chamber 102 is filled with the contained sample 113, at least some of the contained sample 113 in the container chamber 102 can be drawn up, absorbed, or otherwise wicked by at least a portion of the wicking component 134 in a direction of the wick proximal end 140. Since the reference electrode material 132 is disposed at the wick proximal end 140 (see, e.g.,
The method 300 can further comprising placing the assembled sensor apparatus 100 (the assembled sensor apparatus 100 is when the container cap 104 is fastened to the sample-filled container chamber 102) into a container receiving space of the reader 200 in step 300C. For example, a user can lift the lid 206 of the reader 200 to insert the assembled sensor apparatus 100 into the container receiving space of the reader 200.
As previously discussed, when the sensor apparatus 100 is positioned within the container receiving space, a reference electrode contact 216 of the reader 200 (see, e.g.,
The reference electrode contact 216 and the active electrode contact 218 can be electrically coupled to a signal readout control unit 210 (see, e.g.,
At this point, a user (e.g., a laboratory technician or clinician) of the reader 200 can input a desired or target concentration 308 to the reader 200. For example, the user can apply certain touch inputs to the display 204 of the reader 200 to select a preset bacteria concentration level or input the desired or target concentration 308. Also, for example, the user can input the desired or target concentration 308 via a keyboard or other type of input device communicatively coupled to the reader 200. Alternatively, the user can also input the desired or target concentration 308 into a computing device 310 (e.g., a tablet or laptop) communicatively coupled to the reader 200. The computing device 310 can transmit the desired or target concentration 308 to the reader 200 via a wireless communicate protocol or a wired connection.
The desired or target concentration 308 can be a bacterial concentration level required as part of a downstream testing protocol such as an antimicrobial or antibiotic susceptibility test (AST). In certain embodiments, the desired or target concentration 308 can be expressed or displayed as colony forming units (CFUs) per mL. In other embodiments, the desired or target concentration 308 can be expressed or displayed in terms of McFarland standards (e.g., 0.5 McFarland, 1.0 McFarland, 2.0 McFarland, etc.).
In some embodiments, the desired or target concentration 308 can be between about 1.4×108 CFU/mL and 1.6×108 CFU/mL. For example, the desired or target concentration 308 can be about 1.5×108 CFU/mL (also referred to as a 0.5 McFarland standard). In other embodiments, the desired or target concentration 308 can be greater than 1.6×108 CFU/mL or less than 1.4×108 CFU/mL.
In some embodiments, the user can also input certain information concerning a classification (e.g., a genus, family, or order) of the bacteria 302 or a characteristic of the bacteria 302. For example, the user can perform a Gram-stain test of the bacteria 302 prior to introducing the diluted sample 304 into the sensor apparatus 100. The user can then input into the reader 200 whether the bacteria 302 is gram-positive or gram-negative based on the Gram-stain test. In some cases, the reader 200 can retrieve one or more look-up tables (LUTs) tailored to the classification or characteristic of the bacteria 302 provided by the user.
The method 300 can also comprise incubating and aerating the contained sample 113 in step 300D. In some embodiments, the contained sample 113 within the sensor apparatus 100 can be incubated and aerated simultaneously. In other embodiments, the contained sample 113 within the sensor apparatus 100 can begin the incubation period without aeration initially or begin the aeration period without incubation initially. In all such embodiments, there can be a period of time where the contained sample 113 within the sensor apparatus 100 is both incubated and aerated.
The contained sample 113 within the sensor apparatus 100 can be incubated at an incubation temperature. In some embodiments, the incubation temperature can be between about 30° C. and 40° C. (e.g., about 35° C.±2° C.). In other embodiments, the incubation temperature can be between about 25° C. and 30° C. As previously discussed, the sensor apparatus 100 comprising the contained sample 113 can be incubated while housed within the reader 200. For example, the thermal control module 212 of the reader 200 can control the incubation of the sample-filled sensor apparatus 100. The reader 200 can incubate the sensor apparatus 100 by heating at least part of the sensor apparatus 100 via the heating block 220 (see, e.g.,
The contained sample 113 within the sensor apparatus 100 can be aerated at an aeration flow rate or gas dispense rate. The aeration flow rate can be between 7.0 microliter (p L) per second per milliliter (mL) of the contained sample 113 and 10.0 μL per second per mL of the contained sample 113. More specifically, the contained sample 113 within the sensor apparatus 100 can be aerated at a flow rate of about 8.8 (±0.9) μL per second per mL of the contained sample 113. As previously discussed, the contained sample 113 can be aerated using a motorized piston pump. The motorized piston pump can be housed or contained within the reader 200. Aeration of the contained sample 113 can be controlled by the aeration control module 214 of the reader 200.
In some embodiments, the contained sample 113 within the sensor apparatus 100 can be aerated in accordance with an aeration cycle. The aeration cycle can include an aeration period followed by a non-aerated period where no gas or ambient air is pumped into the container chamber 102 (see, e.g.,
In certain embodiments, the aeration period can be longer than the non-aerated period. For example, the aeration period can be between about 7 minutes and 10 minutes and the non-aerated period can be between about 3 seconds and 10 seconds. As a more specific example, the contained sample 113 within the container chamber 102 can be aerated repeatedly at a flow rate or dispense rate of about 10.0 μL per second per mL of the contained sample 113 for a period about 8 minutes followed by a non-aerated period of about 5 seconds.
The method 300 can also comprise monitoring a change in the ORP of the contained sample 113 within the sensor apparatus 100 in step 300E. The ORP of the contained sample 113 can be monitored or measured as soon as the sensor apparatus 100 is positioned within the reader 200 and the user has inputted the desired or target concentration 308. The ORP of the contained sample 113 can be monitored or measured during the pendency of the incubation period and/or aeration period.
As previously discussed, in some embodiments, the signal readout control unit 210 of the reader 200 can monitor the ORP of the contained sample 113 within the container chamber 102 of the sensor apparatus 100. For example, as part of the ORP monitoring process, the ORP of the contained sample 113 can be sampled or determined multiple times per second and such ORP values can be recorded in conjunction with an elapsed time 313. The reader 200 can display the change in ORP as a function of the elapsed time 313 as an ORP growth curve 311. As a more specific example, the ORP growth curve 311 can be rendered and shown to the user via the display 204 of the reader 200 or via a display of a computing device 310 communicatively coupled to the reader 200. As the amount of bacteria in the contained sample 113 increases (the bacterial concentration increases), the amount of reduced molecules/compounds in the contained sample 113 also increases. This, in turn, causes the ORP of the contained sample 113 to decrease or the ORP value to become more negative.
The method 300 can further comprise retrieving a species-agnostic look-up table (LUT) 312 from a database in step 300F. The species-agnostic LUT 312 can be retrieved in response to the user inputting the desired or target concentration 308. In other embodiments, the species-agnostic LUT 312 can be retrieved once the ORP of the contained sample 113 is being monitored by the reader 200. For example, one or more processors of the reader 200 can be programmed to retrieve the species-agnostic LUT 312 from a memory or storage unit of the reader 200. In other embodiments, the one or more processors of the reader 200 can be programmed to retrieve the species-agnostic LUT 312 from a database stored on the computing device 310 or a database in the cloud.
The species-agnostic LUT 312 can comprise a plurality of species-agnostic ORP change amounts 314 and species-agnostic bacterial concentrations 316. Each species-agnostic bacterial concentration 316 can have a species-agnostic ORP change amount 314 associated with the species-agnostic bacterial concentration 316.
The species-agnostic LUT 312 can be constructed or generated from a plurality of species-specific LUTs 406 and/or strain-specific LUTs 404 (see, e.g.,
The method 300 can further comprise determining whether the desired or target concentration 308 is included in the species-agnostic LUT 312 in step 300G. For example, the one or more processors of the reader 200 can query the bacterial concentration field (i.e., the species-agnostic bacterial concentrations 316) in the species-agnostic LUT 312 using the desired or target concentration 308 received from the user. If the one or more processors of the reader 200 determines that the desired or target concentration 308 is included in the species-agnostic LUT 312, the one or more processors of the reader 200 can select one of the species-agnostic ORP change amounts 314 as a threshold ORP change amount 318 when the species-agnostic ORP change amount 314 selected is associated with one of the species-agnostic bacterial concentrations 316 equal or substantially equal to the desired or target concentration 308 in step 300H. In this manner, the reader 200 relies primarily on the species-agnostic LUT 312 to set the threshold ORP change amount 318.
However, if the one or more processors of the reader 200 determines that the desired or target concentration 308 is not included in the species-agnostic LUT 312, the one or more processors of the reader 200 can calculate a time-to-target concentration (ttarget) 320 in step 300I. Calculating the time-to-target concentration 320 will be discussed in more detail in later sections.
In certain embodiments, the one or more processors of the reader 200 can opt to calculate the time-to-target concentration 320 even if the desired or target concentration 308 is included in the species-agnostic LUT 312. For example, the one or more processors of the reader 200 can opt for this calculation based on certain heuristics or preset rules that dictate when the threshold ORP change amount 318 from the species-agnostic LUT 312 is considered too high/too large or may be prone to error. In this case, the one or more processors of the reader 200 can make the determination to calculate the time-to-target concentration 320 rather than rely on certain ORP values (i.e., species-agnostic ORP change amounts 314) from the species-agnostic LUT 312. For example, the one or more processors of the reader 200 can decide that certain smaller species-agnostic ORP change amounts 314 are more accurate or less prone to error based on real-time or near-real-time analysis of the behavior of the ORP growth curve 311 (for example, if the ORP signal monitored is beginning to flatten out). In this case, the one or more processors of the reader 200 can determine that certain smaller species-agnostic ORP change amounts 314 from the species-agnostic LUT 312 are more applicable or less prone to error and use such ORP change amounts in calculating the time-to-target concentration 320.
The method 300 can also comprise determining that the bacteria in the contained sample 113 has reached the desired or target concentration 308 (or within acceptable error margins thereof) in step 300J. For example, the one or more processors of the reader 200 can determine that the bacteria in the contained sample 113 has reached the desired or target concentration 308 (or within acceptable error margins thereof) when either the change in the ORP of the contained sample 113 monitored in real-time or near-real-time by the reader 200 has reached the threshold ORP change amount 318 (or within acceptable error margins thereof) (see, also, step 300H) or when the elapsed time 313 has reached the calculated time-to-target concentration 320 (see, also, step 300I).
The method 300 can further comprise cooling the contained sample 113 within the sensor apparatus 100 when the concentration of the bacteria in the contained sample 113 is determined to have reached the desired or target concentration 308 (or within acceptable error margins thereof) in step 300K. The contained sample 113 can be cooled at a cooling temperature between about 4° C. and 25° C. The sensor apparatus 100 can be cooled within the reader 200. For example, the thermal control module 212 can also be used to cool the contained sample 113 to between about 4° C. and 25° C. Cooling the contained sample 113 is needed to prevent the bacteria within the contained sample 113 from continuing to grow or the bacterial concentration from increasing any further.
Step 300K can also comprise the reader 200 alerting the user that the bacteria in the contained sample 113 has reached the desired or target concentration 308 (or within acceptable error margins thereof) and the output sample is now ready for downstream testing. For example, the reader 200 can comprise a speaker and the speaker can generate an audible alert or sound an alarm to notify the user that the bacteria in the contained sample 113 has reached the desired or target concentration 308 (or within acceptable error margins thereof). In additional embodiments, the reader 200 can render a visual or graphic alert via its display 204 informing the user that the bacteria in the contained sample 113 has reached the desired or target concentration 308 (or within acceptable error margins thereof) and the output sample is now ready for downstream testing.
As shown in
The method steps depicted in
Each of the constituent LUTs 402 can be either a strain-specific LUT 404 or a species-specific LUT 406. A species-specific LUT 406 can be generated from multiple strain-specific LUTs 404 comprising bacteria of the same species. Each of the strain-specific LUTs 404 can be compiled using ORP measurements and bacterial concentration measurements taken concurrently of a reference bacterial sample 408.
In some embodiments, the species-agnostic LUT 312 can be generated from multiple (at least three) strain-specific LUTs 404. In other embodiments, the species-agnostic LUT 312 can be generated from multiple (at least three) species-specific LUTs 406. In additional embodiments, the species-agnostic LUT 312 can be generated from a mixture of strain-specific LUTs 404 and species-specific LUTs 406.
For example, the at least three constituent LUTs 402 can include a first LUT, a second LUT, and a third LUT. Each of the first LUT, the second LUT, or the third LUT can be either a strain-specific LUT 404 or a species-specific LUT 406. The first LUT, the second LUT, and the third LUT can be generated using concurrent ORP and bacterial concentration measurements made or taken of a first reference bacterial sample, a second reference bacterial sample, and a third reference bacterial sample, respectively. The first reference bacterial sample can comprise a bacteria of a first species, the second reference bacterial sample can comprise a bacteria of a second species different from the first species, and the third reference bacterial sample can comprise a bacteria of a third species different from either the first species or the second species.
Each of the constituent LUTs 402 can comprise constituent LUT ORP change amounts 410 and constituent LUT bacterial concentrations 412. In some embodiments, the constituent ORP change amounts 410 can be the same as the species-agnostic ORP change amounts 314. In these embodiments, the constituent LUT bacteria concentrations 412 associated with each of the constituent ORP change amounts 410 can be averaged across the multiple constituent LUTs 402 to obtain the species-agnostic bacterial concentrations 316.
For example,
Although not shown in
Referring back to
In some embodiments, between six and eight reference bacterial samples 408 can be prepared. In other embodiments, nine or more reference bacterial samples 408 can be prepared. The accuracy of the LUTs (including any of the species-specific LUTs 406 and the species-agnostic LUT 312) can be improved or enhanced when more reference bacterial samples 408 are used to generate such LUTs.
The reference bacterial samples 408 can be prepared by re-suspending plated colonies of bacteria of a known species and/or strain into liquid growth media such as the dilutive solution 306. An aliquot (e.g., 1 mL) of the re-suspended bacterial samples can then be introduced into an instance of the sensor apparatus 100. As shown in
The ORP of each of the reference bacterial samples 408 can be monitored by a reader 200. For example, a sensor apparatus 100 containing the reference bacterial sample 408 can be placed within the container receiving space of the reader 200 and the reader 200 can be programmed to monitor changes in the ORP of the reference bacterial sample 408 over a period of time. Concurrent with this monitoring, the optical density (O.D.) of the reference bacterial sample 408 can also be measured at specific time intervals 414. For example, the specific time intervals 414 can be every several minutes such as every 15 minutes. In other embodiments, the specific time intervals 414 can be every 5 minutes, every 10 minutes, every 20 minutes, or every 30 minutes. For example, the ORP of the reference bacterial sample 408 can be monitored over a period of 180 minutes. Concurrent with this monitoring, the O.D. of this reference bacterial sample 408 can be periodically measured every 15 minutes over this 180-minute period.
The reader 200 can incubate and aerate the reference bacterial sample 408 similar to how it incubates and aerates the contained sample 113. The reader 200 can incubate the reference bacterial sample 408 at an incubation temperature of between about 30° C. and 40° C. (e.g., about 35° C.±2° C.). The reader 200 can also aerate the reference bacterial sample 408 between 7.0 μL per second per mL of the reference bacterial sample 408 and 10.0 μL per second per mL of the reference bacterial sample 408. More specifically, the reference bacterial sample 408 within the sensor apparatus 100 can be aerated at a flow rate of about 8.8 (±0.9) μL per second per mL of the reference bacterial sample 408.
In some embodiments, the reference bacterial sample 408 within the sensor apparatus 100 can be aerated in accordance with an aeration cycle. The aeration cycle can include an aeration period followed by a non-aerated period where no gas or ambient air is pumped into the container chamber 102. In certain embodiments, the aeration period can be longer than the non-aerated period. For example, the aeration period can be between about 7 minutes and 10 minutes and the non-aerated period can be between about 3 seconds and 10 seconds. As a more specific example, the reference bacterial sample 408 within the container chamber 102 of the sensor apparatus 100 can be aerated repeatedly at a flow rate or dispense rate of about 10.0 μL per second per mL of the reference bacterial sample 408 for a period about 8 minutes followed by a non-aerated period of about 5 seconds.
In some embodiments, O.D. measurements 417 can be conducted at a wavelength of 600 nm (OD600 measurements) using a spectrophotometry device 416 or system (e.g., UV-Vis spectrophotometry device). In certain embodiments, the sensor apparatus 100 can be removed from the reader 200 at the end of each of the specific time intervals 414 and the reference bacterial sample 408 can be transferred to another container or tube compatible with the spectrophotometry device 416 or system. In other embodiments, the sensor apparatus 100 can be designed or otherwise configured to work directly with certain types of spectrophotometry devices 416 or systems such that the O.D. of the reference bacterial sample 408 can be measured even when the reference bacterial sample 408 is within the container chamber 102 of the sensor apparatus 100.
In some embodiments, the spectrophotometry device 416 or system can be communicatively coupled to the computing device 310 which is, in turn, communicatively coupled to the reader(s) 200. The computing device 310 can record and store the results of the O.D. measurements 417 and the ORP monitoring in one or more databases stored in a memory of the computing device 310 or a cloud-based database accessible to the computing device 310.
In other embodiments, the spectrophotometry device 416 or system can be communicatively coupled directly to the reader 200 and the reader 200 can store the results of the O.D. measurements 417 along with the ORP change amounts.
The O.D. measurements 417 can be converted to reference sample bacterial concentrations 418 (expressed in CFU/mL) using a conversion factor. For example, one or more processors of the computing device 310 can be programmed to convert the results of the O.D. measurements 417 to reference sample bacterial concentrations 418 using the conversion factor. For example, the results of the O.D. measurements 417 can be converted to reference sample bacterial concentrations 418 by multiplying the results of the O.D. measurements 417 by a numerical conversion factor (e.g., O.D.×(1.76×109)). The conversion factors are usually instrument dependent and vary from instrument to instrument.
In certain embodiments, a plate count assay or a flow cytometry assay can be conducted to determine the reference sample bacterial concentrations 418 in lieu of or in addition to the O.D. measurements 417.
The computing device 310 can then generate a strain-specific LUT 404 by associating each of the reference sample bacterial concentrations 418 (converted from an O.D. measurement 417) with a measured change in the ORP of the reference bacterial sample 408. For example, each of the reference sample bacterial concentrations 418 can be associated with a measured change in the ORP of the reference bacterial sample 408 as determined by the reader 200. Moreover, the reference sample bacterial concentrations 418 can then be included as the constituent LUT bacterial concentrations 412 for a particular strain-specific LUT 404 and the changes in the ORP of the reference bacterial sample 408 can be included as the constituent LUT ORP change amounts 410 of this particular strain-specific LUT 404.
This process can then be repeated for each of the other reference bacterial samples 408 until at least three strain-specific LUTs 404 are compiled. In some embodiments, numerous strain-specific LUTs 404 are created which are then used to create multiple species-specific LUTs 406. Such species-specific LUTs 406, or a combination of species-specific LUTs 406 and strain-specific LUTs 404, can then be used to create the species-agnostic LUT 312.
As previously discussed, the LUTs (including any of the species-agnostic LUT 312, the strain-specific LUTs 404, and the species-specific LUTs 406) can be stored as part of a database software program in a memory of the reader 200, the computing device 310, communicatively coupled to the reader 200, or a combination thereof. In other embodiments, the LUTs can be stored as part of a database software program in a computing cloud or a remote server accessible to the reader 200 and/or the computing device 310 over a network.
In some embodiments, multiple species-agnostic LUTs 312 can be prepared. In these embodiments, the species-agnostic LUTs 312 can be organized by genus, family, order, class, phylum, kingdom, or domain. Furthermore, certain species-agnostic LUTs 312 can also be organized by microbial characteristics, such as Gram-type, or functional capabilities, such as the ability to hydrolyze certain proteins or molecules, can also be selected or retrieved.
In preparing the output samples, a threshold ORP change amount 318 (ΔORPThreshold=−60 mV) was selected from the species-agnostic LUT 312 shown in
The average output sample concentration was 1.43×108 (±0.15 log10) CFU/mL. The goal of the trial runs was that at least 95% of the output sample concentrations would fall within ±0.5 log10 of the desired or target concentration 308 of 1.5×108 CFU/mL.
These results show that the method 300 and system 301 (the sensor apparatus 100 and reader 200) disclosed herein is effective at preparing an output sample within acceptable error margins of a desired or target concentration 308. Moreover, these results show that the method 300 and system 301 disclosed herein can also be effective at preparing an output sample within acceptable error margins of a desired or target concentration 308 from a source sample comprising bacteria of a species that was not included in reference bacterial samples 408 used to make the species-agnostic LUT 312. That is, the species-agnostic LUT 312 relied upon to make the output samples is truly “species-agnostic” and has wide applicability to species beyond those used to make the species-agnostic LUT 312.
As will be discussed in the following sections, a large part of the effectiveness of the method 300 and system 301 disclosed herein can be attributed to the aeration protocols disclosed herein.
While
As previously discussed, it should also be emphasized that too much aeration of the contained sample 113 can have detrimental effects on the ORP signal monitored by the reader 200. Therefore, the contained sample 113 within the sensor apparatus 100 should be aerated at a flow rate within an optimal range. One such range discovered by the applicants is a flow rate between 7.0 μL per second per mL of the contained sample 113 and 10.0 μL per second per mL of the contained sample 113. More specifically, the contained sample 113 can be aerated at a flow rate of about 8.8 (±0.9) μL per second per mL of the contained sample 113.
In some embodiments, the contained sample 113 within the sensor apparatus 100 can be aerated in accordance with an aeration cycle. The aeration cycle can include an aeration period followed by a non-aerated period where no gas or ambient air is pumped into the container chamber 102. In certain embodiments, the aeration period can be longer than the non-aerated period. For example, the aeration period can be between about 7 minutes and 10 minutes and the non-aerated period can be between about 3 seconds and 10 seconds.
For the three samples containing facultative anaerobic species of bacteria (ECo, SMa, and PVu), the percentage change in bacterial doubling times is in the range of 15% to 21%. However, for the two samples containing strictly aerobic species of bacteria, Aba and PAe, the percentage change in bacterial doubling times is much higher at 41% and 84%, respectively. In addition, when examining the results for all species of bacteria, when such samples are not aerated (or remain stagnant), the CV in their bacterial doubling times is extremely high at 109%. However, with aeration, the CV in their bacterial doubling times drops to 12% and their growth behaviors (as evidenced through their doubling times) becomes very similar. This is important for the success of the species-agnostic method 300 because it ensures that all results are obtained in a similar time frame, irrespective of whether the bacteria in the source sample is a facultative anaerobe or a strict aerobe.
Each of the bacterial doubling times (e.g., the doubling times for ECo, SMa, PVu, Aba, PAe, etc.) can be calculated using O.D. measurements taken of the various reference bacterial samples 408 (see, e.g.,
N=A(ekt) [Equation 1]
In Equation 1 above, N is the converted bacterial concentration, t is the time in minutes, and A and k are the fit parameters. For purpose of determining the bacterial doubling time (tdoubling), A does not matter since A corresponds to the initial concentration of bacteria (i.e., at t=0) and is not relevant for determining the bacterial doubling time.
The relationship between the bacterial doubling time (tdoubling) and k is provided in Equation 2 below:
As previously discussed, an average doubling time (tdoubling_average) can then be calculated from taking an average of the plurality of bacterial doubling times (tdoubling). The average doubling time (tdoubling_average) is needed to calculate a time-to-target concentration (ttarget) 320 (see, e.g., Step 300I of
As previously discussed, in certain embodiments, the one or more processors of the reader 200 can opt to calculate the time-to-target concentration 320 even if the desired or target concentration 308 is included in the species-agnostic LUT 312. For example, the one or more processors of the reader 200 can opt for this calculation based on certain heuristics or preset rules that dictate when the threshold ORP change amount 318 from the species-agnostic LUT 312 may be considered too high/too large or may be prone to error. In this case, the one or more processors of the reader can make the determination to calculate the time-to-target concentration 320 rather than rely on certain species-agnostic ORP change amounts 314 from the species-agnostic LUT 312. For example, the one or more processors of the reader 200 can decide that certain smaller species-agnostic ORP change amounts 314 determined earlier on in the ORP monitoring are more accurate or less prone to error than larger species-agnostic ORP change amounts 314 obtained later on as part of the ORP monitoring. The one or more processors reader 200 can make this determination based on real-time or near-real-time analysis of the behavior of the ORP growth curve 311 (for example, if the ORP signal monitored is beginning to flatten out). In this case, the one or more processors of the reader 200 can determine that the smaller species-agnostic ORP change amounts 314 from the species-agnostic LUT 312 are more useful or less prone to error and opt to use such ORP change amounts in calculating the time-to-target concentration 320.
The one or more processors of the reader 200 can be programmed to calculate a time-to-target concentration (ttarget) 320 using Equation 3 below:
In Equation 3 above, ttarget (or the time-to-target concentration 320) represents the amount of time required for the contained sample 113 to reach the desired or target concentration 308 (Ntarget), N1 is a species-agnostic bacterial concentration included in the species-agnostic LUT, t1 represents a time required for the ORP of the contained sample 113 to change by a species-agnostic ORP change amount (ΔORP) associated with N1 from the species-agnostic LUT 312, and tdoubling_average is the average bacterial doubling time. t1 can be determined from real-time ORP monitoring conducted by the reader 200 on the contained sample 113.
For example,
For example, 1×108 CFU/mL (or 1.0E+8) can be selected as N1 from the species-agnostic LUT 312 shown in
In this example, the reader 200 can alert the user (e.g., a laboratory technician or clinician) that an output sample of the desired or target concentration 308 or an output sample within acceptable error margins of the desired or target concentration 308 has been prepared.
As shown in
This example shows the usefulness of the method 300 and system 301 when a desired or target concentration 308 is beyond any bacterial concentrations included as part of the species-agnostic LUT 312. However, as previously mentioned, a time-to-target concentration (ttarget) 320 can also be calculated even if Ntarget is included as part of the species-agnostic LUT 312. For example, a time-to-target concentration (ttarget) 320 can be calculated as long as Ntarget is greater than N1 (Ntarget>N1).
In fact, when an N1 is selected that equals Ntarget the time-to-target concentration (ttarget) 320 simply equals t1. That is, the time-to-target concentration (ttarget) 320 is simply the time required for the ORP of the contained sample 113 to change by the species-agnostic ORP change amount (ΔORP) associated with N1 from the species-agnostic LUT 312.
It is important to point out that the time-to-target concentration (ttarget) calculations discussed above is only effective since the growth rates of bacteria within all samples (including the contained sample 113 and all reference bacterial samples 408 used to make the species-agnostic LUT 312) have been made more uniform via the specific aeration protocols disclosed herein. That is, the time-to-target concentration (ta) calculations discussed above significantly leverages the benefits of aeration in arriving at an accurate end result.
A number of embodiments have been described. Nevertheless, it will be understood by one of ordinary skill in the art that various changes and modifications can be made to this disclosure without departing from the spirit and scope of the embodiments. Elements of systems, devices, apparatus, and methods shown with any embodiment are exemplary for the specific embodiment and can be used in combination or otherwise on other embodiments within this disclosure. For example, the steps of any methods depicted in the figures or described in this disclosure do not require the particular order or sequential order shown or described to achieve the desired results. In addition, other steps operations may be provided, or steps or operations may be eliminated or omitted from the described methods or processes to achieve the desired results. Moreover, any components or parts of any apparatus or systems described in this disclosure or depicted in the figures may be removed, eliminated, or omitted to achieve the desired results. In addition, certain components or parts of the systems, devices, or apparatus shown or described herein have been omitted for the sake of succinctness and clarity.
Accordingly, other embodiments are within the scope of the following claims and the specification and/or drawings may be regarded in an illustrative rather than a restrictive sense.
Each of the individual variations or embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other variations or embodiments. Modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present invention.
Methods recited herein may be carried out in any order of the recited events that is logically possible, as well as the recited order of events. Moreover, additional steps or operations may be provided or steps or operations may be eliminated to achieve the desired result.
Furthermore, where a range of values is provided, every intervening value between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. Also, any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. For example, a description of a range from 1 to 5 should be considered to have disclosed subranges such as from 1 to 3, from 1 to 4, from 2 to 4, from 2 to 5, from 3 to 5, etc. as well as individual numbers within that range, for example 1.5, 2.5, etc. and any whole or partial increments therebetween.
All existing subject matter mentioned herein (e.g., publications, patents, patent applications) is incorporated by reference herein in its entirety except insofar as the subject matter may conflict with that of the present invention (in which case what is present herein shall prevail). The referenced items are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtue of prior invention.
Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
Reference to the phrase “at least one of”, when such phrase modifies a plurality of items or components (or an enumerated list of items or components) means any combination of one or more of those items or components. For example, the phrase “at least one of A, B, and C” means: (i) A; (ii) B; (iii) C; (iv) A, B, and C; (v) A and B; (vi) B and C; or (vii) A and C.
In understanding the scope of the present disclosure, the term “comprising” and its derivatives, as used herein, are intended to be open-ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” “element,” or “component” when used in the singular can have the dual meaning of a single part or a plurality of parts. As used herein, the following directional terms “forward, rearward, above, downward, vertical, horizontal, below, transverse, laterally, and vertically” as well as any other similar directional terms refer to those positions of a device or piece of equipment or those directions of the device or piece of equipment being translated or moved.
Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean the specified value or the specified value and a reasonable amount of deviation from the specified value (e.g., a deviation of up to ±0.1%, ±1%, ±5%, or ±10%, as such variations are appropriate) such that the end result is not significantly or materially changed. For example, “about 1.0 cm” can be interpreted to mean “1.0 cm” or between “0.9 cm and 1.1 cm.” When terms of degree such as “about” or “approximately” are used to refer to numbers or values that are part of a range, the term can be used to modify both the minimum and maximum numbers or values.
This disclosure is not intended to be limited to the scope of the particular forms set forth, but is intended to cover alternatives, modifications, and equivalents of the variations or embodiments described herein. Further, the scope of the disclosure fully encompasses other variations or embodiments that may become obvious to those skilled in the art in view of this disclosure.
This application is a continuation of International Patent Application No. PCT/US2022/070339 filed on Jan. 25, 2022, which claims priority to U.S. Patent Application No. 63/141,057 filed on Jan. 25, 2021 and U.S. Patent Application No. 63/212,600 filed on Jun. 18, 2021, the contents of which are incorporated herein by reference in their entireties. This application also incorporates by reference U.S. Patent Publication No. US2019/0293529 A1 published on Sep. 26, 2019 and U.S. Patent Publication No. US2021/0131993 A1 published on May 6, 2021.
| Number | Date | Country | |
|---|---|---|---|
| 63212600 | Jun 2021 | US | |
| 63141057 | Jan 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2022/070339 | Jan 2022 | US |
| Child | 18333423 | US |
