Patent Application
20190211299
The technical field of the present invention is that of devices intended to sample colonies of microorganisms on a gelose culture medium for analysis. The present invention more particularly concerns a sampling end fitting having in its distal part a polymer material sampling tip. The invention also concerns a sampling device including an end fitting of this kind and a sampling process using same.
At present, a colony of microorganisms (bacteria, mold, yeast or the like) cultivated on a gelose culture medium in a Petri dish, or on any other medium, is sampled using tools that can be sterilized or single-use tools such as oeses (also known as loops), sticks, tubes or cones.
However, these tools do not enable reliable and efficient sampling of all types of microorganisms because the latter can have very diverse shapes, sizes, consistencies, structures or appearances.
Moreover, these consumables do not easily enable optimum deposition of the sampled biological substance on analysis media such as plates intended for MALDI-TOF type mass spectrometry analysis. Also, it is also very important to be able to sample a colony of bacteria or a fraction of that sample without sampling the culture medium under the colony. This can in fact falsify the results of subsequent analyses.
The quality of the results of analysis may also depend on the concentration of the deposit of the biological substance, formed from the sample taken, and its homogeneity on the medium on which it is deposited. This is particularly the case for MALDI-TOF microorganism analyses, in which the sample must form a thin and uniform layer to enable optimum analysis.
Oeses that are disposable or can be sterilized by flame are conventionally used to sample a colony of microorganisms on a Petri dish and to deposit the biological substance on the MALDI-TOF plate. This operation is not easy and calls for some dexterity. Gripping a tool of this kind between the thumb and the index finger can cause muscular-skeletal problems. The oese is generally held far from its end so that the hand of the operative does not contaminate the sample, but this position of the hand makes the accuracy of the movement at the end of the oese more difficult, notably when it is necessary to produce a thin and homogeneous deposit over a small area of the order of a few mm2. Finally, the oese, having been designed to sample a calibrated given quantity of microorganisms (generally between 1 μL and 10 μL), includes at its end a metal or plastic loop which has a diameter that is generally greater than 1 mm. This tip can be larger than the surface on which the deposit is to be formed. Moreover, the rigid nature of the (metal or plastic) oese is not particularly suitable for spreading a colony of microbes in a thin uniform layer on a hard surface.
It is also possible to use other consumables such as swabs, wooden sticks, micropipette end fittings.
Thus, the document U.S. Pat. No. 9,181,522 describes a process and an apparatus for the aseptic transfer of biological substances. The apparatus is composed of a double-walled chamber for housing end fittings of a single size having a ball at the head end, intended for the transfer of the biological substance from one place to another, in an aseptic manner. A first disadvantage of a device of this kind is that is of relatively complex design, with an integral system for UV sterilization of the end fittings, its double-wall architecture and its system for internal loading and ejection of the end fittings. Such complexity undoubtedly impacts the unit cost and therefore the selling price. Moreover, the material used to make the ball present at the head end of the disposable end fitting is made of a hard material, of metal or polypropylene type, which is not propitious for the sampling process but above all for depositing a biological substance, such as a colony of bacteria, notably on a MALDI-TOF type mass spectrometry analysis plate.
The document FR 2 668 495 describes a sterile sampling cone for bacteriological use. Said cone has at its distal end a solid protuberance that is slightly frustoconical, off-axis relative to the longitudinal axis of the cone. This protuberance enables the sampling of a biological substance. To this end, in one particular embodiment, it may include an optional loop. Even with a particular architecture, the cone described in the above document is nevertheless still made of a material conventionally used for this kind of product. Namely a hard and smooth plastic material that is not suited to sampling and depositing biological substances. Moreover, its particular shape does not make it easy to use to deposit a biological substance, such as a colony of bacteria over a very small area, such as a MALDI-TOF mass spectrometry analysis plate.
The applicant has previously resolved all or some of the disadvantages referred to above by proposing a process for sampling all or some of a sample of a biological substance grown in contact with a gelose culture medium, which uses a probe provided with a terminal end. Said sampling process is essentially based on cooling the terminal end of the probe, enabling sticking of all or part of the sample of the biological substance to be sampled by contact of the terminal end with the sample of the biological substance or by application of a pressure exerted by the terminal end on the sample of the biological substance, followed by releasing all or some of the sample of the biological substance by heating the terminal end of the probe. This process is described in the patent application WO 2012/004545.
The main disadvantage of this process is that it necessitates relatively bulky equipment for cooling the probe, which consumes energy and represents a high financial cost.
The result of the analysis of the prior art is that at present there exists no system for sampling a biological substance that is easy to use, of simple design and employs a disposable sampling end fitting having physical properties suited to optimizing not only sampling but also depositing a biological substance such as a colony of bacteria.
The objectives of the present invention are therefore to address these lacks by proposing an end fitting that is of simple design, easy to produce, enables when placed on a device for sampling a biological substance precise sampling and deposition of that biological substance, notably on a MALDI-TOF type mass spectrometry analysis plate.
These objectives, among others, are achieved by the present invention, which firstly concerns an end fitting capable of being fitted to the body of a manual or automated device for sampling a biological substance of microbial origin, comprising:
a) a distal end comprising a means for sampling a biological substance of microbial origin,
b) a proximal free end intended to come into contact with the body of said sampling device and to enable the attachment of said end fitting to said body,
said end fitting being characterized in that all or some of the free distal end consists of a fibrous material having a porosity at least equal to 30%.
By a biological substance of microbial origin is essentially meant a biological substance consisting of bacteria, yeast or mold.
In one advantageous embodiment, the end fitting according to the invention consists entirely of a fibrous material having a porosity at least equal to 30%.
The fibrous material preferably has a porosity greater than 50%, preferably greater than 70%.
The fibrous material is advantageously selected from the group comprising: polyethylene, polyesters, polyethylene terephthalate (PET), PET/polyethylene copolymer, PET/PET copolymer, polyamide, cotton.
The sampling end fitting has a substantially conical or frustoconical overall shape. For its part, the sampling means is advantageously of cylindrical, frustoconical or spherical overall shape.
Another object of the present invention concerns a device for sampling a biological substance of microbial origin comprising:
an end fitting according to the invention
a body including at least:
a proximal part serving at least partially as a zone for gripping said device, and
a distal part having a free end to the end of which said end fitting is attached.
This device further includes a system for ejecting the end fitting. The ejection system advantageously includes a rod positioned inside said body and mobile in translation, so as to press on the end fitting and thus to eject it.
In one particular embodiment, said rod is mobile in translation by means of a pushbutton.
Another object of the invention concerns a process for sampling a biological substance of microbial origin comprising the following steps:
a) Positioning an end fitting according to the invention on the distal part of the sampling device,
b) Positioning the sampling device in the vicinity of a colony of a biological substance of microbial origin present on a culture medium in order to bring the sampling means of said end fitting into contact with the biological substance,
c) Sampling all or some of the biological substance with the aid of the sampling device, so that the sampled biological substance is attached to the sampling means.
Another object of the present invention concerns a process for preparing an analysis plate for MALDI-TOF type mass spectrometry microbiological analysis from a sample of a biological substance, comprising the following steps:
a) Positioning an end fitting on the distal part of the sampling device according to the invention,
b) Positioning the sampling device in the vicinity of a colony of a biological substance of microbial origin present on a culture medium in order to bring the sampling means of said end fitting into contact with the biological substance,
c) Sampling all or some of the biological substance with the aid of the sampling device, so that the sampled biological substance is attached to the sampling means,
d) Uniformly depositing the sampled biological substance on at least one analysis zone of a MALDI-TOF type mass spectrometry analysis plate, by bringing the sampling means into contact with the surface of said at least one analysis zone.
By microbiological analysis is essentially meant any analysis enabling identification of a microorganism, such as a bacterium or a yeast, but also enabling highlighting of any antimicrobial resistance marker, any characteristic of typing or of expression by said microorganism of a virulence factor.
Another object of the invention concerns a process for isolating a biological substance of microbial origin on a gelose culture medium, comprising the following steps:
a) obtaining a sample of a biological substance in contact with the sampling means of the end fitting of a sampling device according to the invention,
b) Positioning the sampling device in the vicinity of the surface of the gelose culture medium, so that the sampling means is in contact with said surface,
c) Moving the sampling device so that the sampling means is moved over the surface of the culture medium, while remaining in contact therewith, thereby releasing all or some of the sample of a biological substance in contact with said sampling means onto said surface of the culture medium.
In one particular embodiment, all of the processes described supra further include a final step of ejecting the sampling end fitting.
The sample of a biological substance may be obtained form a colony of a biological substance, by the sampling process described supra.
Alternatively, the sample of a biological substance may be obtained from a suspension of a biological substance. A suspension of this kind is traditionally obtained by putting one or more colonies of a biological substance into suspension in a saline solution. In accordance with this alternative, the sampling end fitting is dipped into a fraction of the suspension, in order to enable absorption of the liquid by the sampling means, thanks to the absorbing power of the fibrous material constituting said sampling means. The biological substance is then in contact with said sampling means. The concentration of the bacterial suspension is determined by the person skilled in the art according to the growth characteristics of the microorganism concerned. This forms part of their general background knowledge. Likewise, the suspension fraction used to charge the end fitting with biological substance is also determined deliberately. It is advantageously from a few microliters to a few tens of microliters.
The aims and advantages of the present invention will be better understood in the light of the following detailed and nonlimiting description of the invention given with reference to the drawings in which:
La
In
The end fitting 10 may be molded from the materials usually employed for molding pipette end fittings. The material may for example be a polymer of polyolefin type. This type of material is generally inexpensive, can be sterilized and is suitable for use for the production of single-use products.
Regarding the sampling means 14, the material constituting the latter is very important. In fact, the sampling means has the two-fold technical constraint of having to provide for sampling a biological substance, such as a colony of bacteria, but also releasing said biological substance when it is deposited on an analysis device such as a mass spectrometry analysis plate. Thus the inventors discovered that the porosity of the material used to manufacture the sampling means 14 was an essential feature to enable a good compromise to be achieved between performance in terms of sampling and releasing the biological substance.
Moreover, over and above the inherent features of the sampling means, it is important to keep in mind that when the biological substance to be sampled is a colony of bacteria, how the latter behaves during sampling or during deposition can vary from one bacterial space to another. It is in fact well known that colonies of bacteria are more or less consistent, more or less viscous, more or less thread-like depending on the bacterial space concerned. It is therefore essential to have a sampling means that is able to manipulate any type of colony of bacteria, whatever its properties.
Thus the inventors established that a porosity at least equal to 30% was necessary to obtain the required properties. Ideally a porosity at least equal to 70% enables the best results to be obtained.
By porosity of the material is meant all of the voids (pores) of a solid material that can be filled with a fluid (liquid or gas). We also mean by porosity the physical parameter defined as the ratio between the volume of the voids and the total volume of the porous medium concerned.
The porosity of the material is measured in the following manner:
A sample of the dry fibrous material is taken.
The sample is weighed a first time.
The sample is immersed in water long enough to impregnate it completely.
The impregnated sample is weighed again.
The mass of water trapped in the material is deduced by calculating the difference between the mass of the impregnated material and that of the dry material.
The mass per unit volume of water being close to 1, there is deduced from this the volume of water trapped and thus the volume of the voids in the material.
The volume of the impregnated sample is then measured.
By dividing the value for the voids in the sample of material obtained above via the measured volume of the impregnated sample it is therefore possible to obtain the value of the porosity of the material.
The materials particularly suitable for producing the sampling means may be fibrous materials. Among these materials may be cited synthetic materials such as polyethylenes, polyesters, polyamides. Among the polyesters may be mentioned polyethylene terephthalate (PET). They may also be copolymers, such as polyethylene/polyester polymers, such as a polyethylene/PET copolymer or again a PET/PET copolymer. When it is a question of a fibrous material, the fibers may consist of a mono-component or bi-component material. A bi-component fiber may for example consist of a PET core and a polyethylene sheath.
Natural fibrous materials may equally be used. This is the case of cotton fibers in particular.
A second embodiment of the end fitting is represented in
According to a variant embodiment of the sampling end fitting 11, the proximal end 13 may include an orifice enabling a hole to be generated passing between the distal and proximal ends. It is then possible to use a longer sampling means, positioned in the through-hole and fastened to the end fitting at the level of the orifice at the proximal end, or even at both ends. A variant of this kind is of simpler design and therefore less costly to manufacture.
The sampling means 14 represented in
According to one variant of the invention, a sampling end fitting consisting entirely of porous material could be envisaged. According to this variant embodiment, the sampling end fitting would also constitute the sampling means.
According to another variant of the invention, the sampling means, the sampling end fitting and the sampling device could be one and the same. In fact, a single-use sampling device could be envisaged to which a porous sampling end fitting is fastened. Alternatively, the sampling device may be made entirely of porous material. To this end, the dimensions of the sampling means must allow easy gripping and manipulation.
The sampling end fitting conjugate with the sampling means or the sampling means alone, if it is in one piece with the sampling end fitting, may be adapted to be used in an automated system for sampling a biological substance. A system of this kind could for example sample automatically colonies of bacteria on Petri dishes and prepare mass spectrometry analysis plates.
In
As represented in
The blades 401 are longer than the intermediate part 34 so that when the rod 40 is positioned inside the body 38 the free top ends of the blades 401 emerge from the openings 382. These free ends are fastened to the pusher member 36 when the spring is in place. This fastening may be mechanical. Accordingly, placing radially projecting lugs in the vicinity of the free end of the blades 401 that come to be housed in openings formed in the internal wall of the pusher member 36 may be envisaged. Alternatively, it is possible to fasten the free ends of the blades 401 to the internal face of the pusher member 36 by chemical bonding.
As represented in
The various steps of the process for using the sampling device 30 with a sampling end fitting 10 may therefore be summarized as follows:
An end fitting 10 is positioned on the free end 32 of the sampling device. This step is generally carried out by positioning the device vertically in line with a sterile end fitting, generally positioned on a suitable support. The end of the distal part 32 of the sampling device is then inserted into the cavity 24 of the proximal part 20 of the end fitting 10 until it abuts on the bottom of the cavity 24.
To sample a biological substance such as colony of microorganisms on a gelose culture medium, the sampling device is positioned so that the sampling means of the end fitting comes into contact with the colony of microorganisms. All or part of the colony is then sampled.
To deposit all or part of the sampled biological substance on a surface such as the surface of a MALDI-TOF mass spectrometry analysis plate, the sampling device is moved toward said surface, so that the end of the sampling means carrying the biological substance comes into contact with the surface. Small circular movements are then performed with the sampling device to deposit a layer of the biological substance on said surface.
Once the deposit has been applied, the sampling end fitting is ejected by actuating the ejection means and thrown into a bin. In the case of the sampling device as represented in
A second embodiment of the sampling device is represented in
The rod 56 is inserted in the body 52 via the proximal end of the latter, the coil spring 58 being inserted first. Said coil spring 58 comes to be positioned so that it bears against the fins and the upper part of the distal end 521. Once inserted, the rod 56 comes to be positioned so that it straddles the spring so that the attachment lugs 561 come to cross the interstitial spaces defined between the fins and emerge at the base of the body 52 around the free end 521. A ring 60 is fitted around the free end 521. This ring 60 has three openings 601 intended to receive the end of the attachment lugs 561. The attachment lugs have at their end radial tabs 5611 which once the lugs are positioned inside the ring 60 will come to be locked into the openings 601 and thus fasten together the ring 60 and the rod 56. Alternatively, and with the aim of simplifying the mechanism, it is entirely possible to replace this mechanical fastening system with a system including lugs with no tabs stuck to the ring. As represented in
As in the first embodiment of the sampling device 30, when pressure along the longitudinal axis of the sampling device is exerted on the pushbutton 54, this pressure is transmitted to the rod 56 fastened to the pushbutton 54. The latter then comes to slide inside the body 52, thus compressing the coil spring 58. This sliding is manifested at the distal end of the sampling device by movement in translation of the ring 60, so that the latter comes to bear on the proximal end of the end fitting 10 and to drive the latter in translation until it is detached from the distal end 521 of the sampling device 50. When the pressure exerted on the coil spring 58 by the rod 56 is released, because the pressure on the pushbutton 54 is released, the latter spring resumes its rest position. The rod 56 is driven in the reverse translation direction by the pressure of the spring until the ring 60 comes to bear against the body 52, rendering the distal part 521 accessible again to receive another sampling end fitting 10.
A third embodiment of a sampling device is represented in
The pushbutton 74 has an inverted “U” shape cross section, intended to enable it to be positioned around and straddling the proximal part 761 of the rod 76, particularly at the level of the inclined shoulders 7611. The pushbutton 74 has on each of these two lateral faces three lugs 741 intended to prevent it escaping, once position in the housing 722. When the rod 76 and the pushbutton 74 are positioned in the body 72 of the sampling device 70, the pushbutton 74 comes to bear at the level of its distal part against the inclined shoulders 7611, preventing the rod 76 from escaping. The interaction between the pushbutton and the inclined shoulders 7611 enables movement of the rod 76 between a rest position and a position for ejecting the sampling end fitting 10. In fact, when an end fitting 10 is positioned on the distal end 721 of the sampling device 70, the latter comes to bear against the ring 78. The latter is then positioned at a high position, against the body 72, as shown in
When the user of the sampling device 70 wishes to eject the sampling end fitting 10, they exert pressure on the pushbutton 74. This pressure leads to the pushbutton being depressed in the housing 722, which then slides on the inclined shoulders 7611. The pushbutton being unable to move laterally, its sliding on the inclined shoulders 7611 leads to movement of the rod 76 in horizontal translation toward the distal end of the body 72. The rod then goes from its rest position to its position for ejecting the end fitting, in which the ejection ring 78 is again in a low position after it has exerted pressure on the end fitting, and this leads to ejection of the latter, as represented in
A fourth embodiment is represented in
Other embodiments of the sampling device can be envisaged. Accordingly, one possible other embodiment consists in positioning at the distal end but on the body at its external part a mechanical system intended to come to bear against the end fitting to allow its ejection. For example there a sleeve mobile in translation on the body of the sampling device may be in contact with the sampling end fitting and enables the latter to be ejected when it is moved by the user.
Other protocols for preparation of samples of a biological substance with a view to analysis using the sampling device may be envisaged. Accordingly, once the biological substance has been sampled, it is possible to prepare a suspension of the biological substance in an ad hoc solution, such as a saline solution. To do this, releasing the sampling end fitting carrying the biological substance directly into a tube containing a quantity of solution in suspension may be envisaged. Vortex agitation of the tube containing the end fitting will then enable release of the biological substance retained on the fibrous material.
The sampling device can also be used to carry out isolation on gelose culture media. This isolation may be carried out directly from colonies sampled with the sampling device according to the invention and then directly reseeded on a gelose culture medium. It can equally be produced from suspensions of a biological substance, produced with the aid of the sampling device, as described supra.
When the sampling device is used to carry out isolation, it is preferable for the sampling means to have a spherical end and to be of sufficient diameter at its end to prevent pressing it against the gelose culture medium coming to damage the latter. A suitable diameter is for example between 2 and 7 millimeters (mm) and advantageously between 2 and 4 mm.
Isolation may be effected from a suspension of bacteria the concentration of which is, for example, 107 CFU (Colony Forming Units)/mL (milliliter). With such a concentration, a sample of 5 microliters (μL) of suspension using the sampling means is sufficient to enable isolation of good quality on the gelose culture medium. The 5 μL of suspension is aspirated by the material constituting the sampling means. Said sampling means charged with suspension can then enable the progressive release of that suspension when it is applied to the gelose culture medium. This progressive release is allowed thanks to the absorbent nature of the material constituting the sampling means. The consequence of this is improved isolation quality.
The isolation may be done in accordance with the traditional techniques, such as the so-called “dial” technique or the so-called “spiral” technique.
The sampling device used in this example is the device represented in
The sampling end fitting is made of plastic material, such as those conventionally used to produce disposable pipette end fittings. It includes a sampling means of cylindrical shape of 2 mm diameter and 6 mm length. It consists of fibers of polyethylene terephthalate (PET)/PET copolymer, a material marketed by the company Porex under the reference PSU-832.
The body of the sampling device is injection molded from polypropylene. It has a length of 120 mm and a section of hexagonal shape with 8.2 mm between the opposite faces of the hexagon, which allows easy gripping like a pencil, with no risk of muscular-skeletal problems.
The sampling device is used to sample colonies of different species of bacteria, which have grown on Columbia agar+5% sheep blood (COS cell line) culture medium, marketed by the applicant under the reference 43041.
The sampled colonies are deposited on a disposable MALDI-TOF analysis plate with 48 positions, marketed by the applicant under the reference 410893.
Of the species chosen, some are known to form colonies that are difficult to sample. This is the case for example with Bacillus lichenformis, Klebsiella pneumoniae, Proteus mirabilis or again Nocardia asteroides.
The process is carried out in accordance with the following steps:
1. A sampling end fitting is positioned on a sampling device.
2. A colony of bacteria is sampled on a COS cell line type culture medium, with the aid of the sampling device, by bringing the sampling means made of fibrous material carried by the sampling end fitting into contact with the colony.
3. The bacterial sample is deposited on the MALDI-TOF analysis plate, in one of the 48 positions provided for this purpose, by bringing the sampling means carrying the bacterial sample into contact with the MALDI-TOF plate, exerting pressure and spreading the sample. The pressure exerted on the fibrous material of the sampling means enables retention of surplus sample on said fibrous material. It is possible to carry out successive depositions at different positions on the analysis plate when it wished to replicate the analysis. These other deposits may be applied using the same end fitting.
4. When all the deposits have been applied, the sampling end fitting is ejected into a bin by exerting pressure on the pushbutton, as described supra.
5. 1 μL of matrix (alpha cyano 4-hydroxycinnamic acid ready for use, bioMerieux reference 411071) is deposited on each deposit of the biological substance, with the aid of a micropipette.
6. Steps 1 to 5 are repeated for each colony that it is wished to analyze,
7. An E. coli ATCC 8739 strain used for calibration and as a positive control is also deposited in accordance with steps 1 to 5.
8. The analysis plate is stored for the time necessary for the matrix to dry.
9. When the plate is entirely dry, it is introduced into the MALDI-TOF VITEK® MS mass spectrometer marketed by the applicant and the mass spectra are acquired.
10. The microorganisms are identified by spectrum analysis using the expert system and the VITEK® MS database.
The same colonies of bacteria are analyzed using the traditional process for MALDI-TOF analysis plate preparation employing an oese and well known to the person skilled in the art.
The results obtained with the two analysis plate preparation methods are set out in TABLE 1 and compared.
The symbol “✓” signifies that the spectrum is of good quality and enables the expected identification of the species.
The symbol “X” means that the spectrum is not of sufficient quality to enable identification of the species.
B. lichenformis
E. aerogenes
E. coli
E. faecalis
K. oxytoca
K. pneumoniae
K. pneumoniae ssp ozaenae
N. asteroides
N. farcinica
P aeruginosa
P. mirabilis
S. aureus
S. epidermidis
It follows from the analysis of Table 1 that, using the protocol employing the sampling device according to the invention, all the species analyzed are correctly identified by mass spectrometry using the VITEK® MS.
By comparison, with the traditional protocol using an oese to sample colonies of bacteria, only 6 species of 13 analyzed are correctly identified. Of the species not identified, a majority are those known to form colonies difficult to manipulate.
In a particularly advantageous manner, the process for the invention therefore enables sampling and depositing of bacteria species forming colonies with an atypical consistency. Accordingly, it is possible easily to obtain excellent identification by MALDI-TOF mass spectrometry results powdery and crust-forming species such as B. lichenformis or N. farcinica, adherent species such as K. pneumoniae and species that diffuse on gelose such as P. mirabilis.
It is also found that the time necessary to deposit 48 samples is shorter with the sampling device according to the invention (12 min) than with an oese (16 min).
The process for the present invention is therefore more ergonomic, easier to use, faster and enables better results to be obtained than the prior art reference process.
In this example, a plurality of fibrous materials having different porosities were tested, notably for their capacity to enable effective sampling of biological substances coming from colonies of different species of bacteria, but equally in their ability to produce a homogeneous deposit on a MALDI-TOF analysis plate. In fact, the performance in identification of species of bacteria by MALDI-TOF mass spectrometry is directly linked to the quality of the deposit of the biological substance on the analysis plate whatever the quantity of material or the homogeneity of the deposit.
The various species were therefore subjected to MALDI-TOF mass spectrometry analysis in order to identify them.
The analysis protocol is that described for example 1, including the sampling device.
The materials tested are set out in TABLE 2 below:
In TABLE 2 are indicated the dimensions of the samples of materials used. Moreover, the values enabling calculation of the porosity by the method indicated supra have also been indicated.
The material PSU892 is a material obtained from two-component fibers, consisting of a polyethylene terephthalate envelope and a polyester core. A material of this kind is marketed by the company POREX®. It is moreover described in the patent application WO-A-03/080904.
The material XA-20521-PS is a material based on polyethylene. A material of this kind is marketed by the company POREX® under the trade name NIBS.
In order to carry out the tests, three different species of bacteria were used:
These species were each seeded on a Columbia gelose culture medium containing 5% of sheep blood (COS), marketed by the applicant under the reference 43041.
For each species, a colony is sampled with the sampling device according to the invention and four deposits are made at four contiguous positions of the MALDI-TOF analysis plate.
The results are set out in TABLE 3 below:
Staphylococcus
Aureus
Klebsiella
pneumoniae
Escherichia coli
Staphylococcus
Aureus
Klebsiella
pneumoniae
Escherichia coli
Staphylococcus
Aureus
Klebsiella
pneumoniae
Escherichia coli
It is seen that for the materials having a high porosity value (greater than 70%), identification performance is excellent, in that all of the species are correctly identified. This is the case with cotton or the material PSU 892.
On the other hand, when materials are used having lower porosity values, the identification performance is found to be impacted. Accordingly, with the material XA-20521-PS which has a porosity of 39%, it is seen that two of the four deposits of Escherichia coli did not allow the identification of this bacterium. Thus there results an identification rate of only 83.3%.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16174789.4 | Jun 2016 | EP | regional |
| 16192227.3 | Oct 2016 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/064633 | 6/14/2017 | WO | 00 |
