Patent Application
20070269849
This invention relates to air-impacting sampling devices. Such devices are generally called bio-impactors. They are generally used for sampling micro-organisms in the air, this air being sucked in so that it impacts on a culture medium, for example agar contained in a Petri dish. Microbiological analysis of the air is carried out by observation of the microorganisms which develop in the culture medium.
The Petri dish is generally arranged inside a removable head. The head comprises an air inlet for the air, opposite the culture medium, and an air suction outlet at the rear of the dish. The air inlet generally comprises a screen comprising orifices for the passage of air, the number, size and arrangement of which orifices are chosen as a function of a sampling protocol.
The head must be completely sterile in order that any microorganisms originating from the head and not from the analyzed air, will not falsify the analysis. The head must therefore be sterilized between each sampling operation. The sterilization of the head by oven heating, as envisaged by current protocols, requires time, equipment and delicate handling on the part of an operator who is generally also responsible for the sampling operation. Very often this sterilization by oven heating is not carried out, the operator being content to clean the head with a disinfectant product. However, apart from the fact that the disinfection may therefore be incomplete, disinfectant can remain on the screen and be carried along by the air as far as the culture medium, which becomes at least partially sterile. The analysis thereof is thus falsified. In order to avoid this drawback, the operator is obliged to carry out several successive sampling operations in order to be able to verify them with each other.
The purpose of the invention is to propose a sampling method and/or device, making it possible to simplify the sampling protocols, whilst ensuring that the culture medium is not polluted by microorganisms foreign to the analyzed air or by a disinfectant product.
According to a first subject of the invention, such a method for sampling air with a view to microbiological analysis is such that:
This method is characterized in that the head is changed between each sampling operation, i.e. the head is replaced with a new head.
The Petri dish can be provided fitted in the head and supplied thus, for example in a sterile package. The Petri dish can be supplied already with the culture medium, this medium being for example in the form of agar. In another method of implementation, the head can be supplied without the culture medium or even without the dish, which allows the operator to use his own culture medium, according to his choice.
The head is therefore provided disposable, produced from inexpensive materials and using inexpensive methods. In order to avoid voluntary or involuntary reuse of the head, once the sampling operation has been carried out, the head is preferably destroyed. The destruction can occur automatically depending on the needs of the analysis, for example on removing the dish in order to be able to observe the microbiological cultures therein.
The head is preferably obtained sterile during manufacture. For example, it can be manufactured in a sterile environment and/or sterilized, in particular by gamma radiation.
In order to maintain the sterility of the head, and particularly if it contains a culture medium, an air inlet and/or a suction outlet on the head can be closed, during its manufacture, with a cap which is removed before the sampling operation and/or assembling the head, respectively. This cap is preferably designed so as not to be repositionable, in order to limit the possibilities for reuse of the head. In another embodiment, the cap can be repositionable in order to be able to avoid pollution or drying-out of the culture medium, after the sampling operation. It can also be packaged in sterile manner, for example in a hermetically sealed sachet.
According to a second subject of the invention, a sampling device according to the invention comprises a single-use head to be used in a method as previously characterized. The head can comprise destructible means making it unsuitable for more than one sampling operation. If the Petri dish is fitted in the head, the destructible means comprise means for holding the dish in the head, said destructible means being designed to be destroyed during the removal of the dish with a view to analysis of the sample. These holding means can be provided for fitting of the dish in the head by clipping. They can be in the form of claws.
In another embodiment, the dish is cast in a single piece with the head. In this case too, the means for holding the part of the head forming a dish relative to the remainder of the head can be provided so as to be destructible. A cover forming an air inlet can be fitted on the head opposite the culture medium in the dish. Before it is put on, this cover in particular allows access to the dish for putting the culture medium in it and/or after its removal for observation of the cultures. The destructible means can comprise means for fixing the cover on the head.
In order to be able to use a device according to the invention with a bio-impactor of the prior art, adapting means can be provided for fixing the head onto the body of the bio-impactor.
Advantageously, a device according to the invention can comprise at least two heads, the first of which comprises a suction outlet suitable for being fixed onto the body of a bio-impactor, and a second head, the first and the second head comprising a complementary air inlet and suction outlet respectively in order to fit the suction outlet of the second head onto the complementary inlet of the first, for example by fitting together. The device can comprise at least two second heads, comprising a complementary inlet and outlet for fitting one in a cascading manner over the other. By way of example, the complementary inlets and outlets are substantially tapered, and are fitted one over the other by wedging one cone into the other.
The head can comprise means for adapting an isokinetic sampling probe to it. The device can be designed in order to be arranged in a flow of air virtually without disturbing said air flow. It can comprise means for improving its aerodynamism, and/or the head can itself be substantially aerodynamic in shape. This is particularly advantageous for carrying out sampling operations in a unidirectional flow, in particular in a laminar flow.
In particular in agri-food or pharmaceutical production lines, sampling operations are carried out regularly, at strategic points on the line. According to a third subject of the invention, a sampling system comprising a fixed pipeline and a suction pump can advantageously be provided. The pipeline is then arranged in order to link one or more locations provided for fixing there a device according to the invention with said pump. Thus, the sampling operations are carried out systematically at the same point, with the same position of the head and their results can be compared. The sampling conditions are therefore made reproducible. Moreover, it is sufficient for an operator to fix a sampling device according to the invention at each location provided, then to simultaneously carry out the sampling operations at these locations. Such a system advantageously comprises means for regulating the flow rate of air in the pipeline. The regulation can be independent for each location, in particular depending on a sampling protocol. Such a system can also be used at a work station, in a clean room or in an operating area. The sampling operations can be carried out continuously, over a given period or at regular intervals.
By the term air in this description is meant any gaseous mixture capable of being analyzed using a device according to the invention, or using a method according to the invention.
Other features and advantages of the invention will also be apparent from the description hereafter, relating to non-limitative examples.
In the attached drawings:
Each of the two parts 1, 2 is moulded from a single piece which is made of a plastic material.
The first part comprises an outer wall 11 in the form of a cylinder with an axis X11. The cylinder is open at a first end 12. This end forms a suction outlet 12 for the first part 1. The first part 1 comprises, at a second end of the cylinder, axially opposite to the first end, an annular wall 13 extending radially towards the axis X11 of the cylinder 11, between the outer wall 11 and a circular inner edge 16 of the annular wall 13.
A screen 14 serves as an inlet for the air to be sampled. This screen is in the shape of a disc perforated with orifices 15, distributed substantially over the whole disc, for the passage of air. The screen is arranged between the two ends of the cylinder 11. The outer edge 17 of the screen 14 is connected to the inner edge 16 of the annular wall, by a tapered connecting wall 18. The tapered wall cone 18 widens from the outer edge 17 of the screen towards the inner edge 17 of the annular wall 13.
The first part is provided for fitting therein a substantially cylindrical Petri dish 3 containing agar 30 forming a culture medium for micro-organisms.
The first part 1 also comprises means for holding a Petri dish 3. These holding means comprise three flat ribs 31 extending radially from the outer wall 11, and parallel to the axis X11 from the annular wall 13. The holding means also comprise three claws 34, each claw extending from a respective rib 31, parallel to the axis X11.
The three ribs and associated claws are substantially identical with each other. They are distributed regularly around the axis X11. The ribs form, each with a claw, an angle bracket 32, 33 a longitudinal edge 32 of which, i.e. parallel to the axis X11, has a length L32 approximately equal to the thickness E3 of the Petri dish 3 provided to be held there. The radial distance between the longitudinal edge 32 and the axis X11 is substantially equal to the radius R3 of the Petri dish 3. A radial edge 33 of the angle bracket extends between the tapered wall 18 and one end of the longitudinal edge closest to the annular wall 13.
Each claw 34 is connected to its rib by a connecting zone 35 with a narrowed section. The claw also comprises a support edge 36, extending radially from the other end of the longitudinal edge 32, opposite the radial edge 33. A bevelled edge 37 extends it from the support edge 36 away from both the axis X11 and the annular wall 13.
During the fitting of the dish 3 in the first part 1 of the head, the dish is supported against the bevelled edges, pushing back the claws which bend is a substantially elastic fashion at the level of the connecting zone 35. When the dish buts up against the radial edges 33, the claws bend back in such a manner that the dish 3 is held axially, gripped between the radial edges 33 and the support edges 36. Moreover, the dish is centred radially between the longitudinal edges 32.
The screen is positioned in the first part in such a manner that, when the dish is fitted, the screen is inside the dish 3, opposite the surface of the agar intended to receive the micro-organisms.
During the removal of the dish it is necessary to break the claws in order to release the dish. The first part is then unusable. This first part must therefore be systematically changed in order to carry out a new sampling operation. It is this first part, extending from upstream to downstream of the Petri dish relative to the flow of air during the sampling operation, which is likely to introduce contamination onto the agar. Its replacement with a new first sterile part makes it possible to ensure that such contamination does not occur.
This second part 2 comprises an annular disc 21, with a hole drilled through its centre. A fitting cylinder 22, complementary to the outer wall 11 of the first part 1 extends from one side of the annular disc 21. This cylinder 22 is provided in order to be inserted inside the outer wall 11, by fitting together and wedging, in substantially airtight manner.
A fixing cylinder 23, extends from the other side of the disc in order to be fixed in substantially airtight manner on a complementary intake, not shown, of a suitable bio-impactor.
A device according to the invention then comprises, besides the head 1, adapting means 6 for fixing the head 1 on the bio-impactor 5. In the example illustrated, the adapting means comprise a ring 61. This ring 61 comprises a bearing surface 62, fixed in substantially airtight manner against the bio-impactor 5, centred around a suction port 51 of the bio-impactor.
The ring comprises a cylindrical inner surface 63 the diameter of which is slightly greater than the outer diameter of the outer wall 11 of the head 1. An O-ring 64, fitted in the ring 6 is flush with the cylindrical surface 63, in such a manner that when the head 1 is fitted on the bio-impactor, the joint forms an airtight seal against the outer wall 11 of the head, and elastically holds the head 1 on the bio-impactor 5.
The device 7 illustrated in
Such a device 7 is particularly suitable for collecting in the first head micro-organisms which, on account of their nature, size, or air flow conditions in the device, have not been able to be collected in the second head 8. Other second heads can be fitted in a cascading manner on the second head 8 described previously, in order to refine the sampling operation.
In order to guarantee the sterility of the zones of the path of the air in the head, a first cap can be provided, attached in a removable manner onto the annular wall 11 of the first part 1, and a second cap can be attached in a removable manner so as to block off the first end 12 of the cylinder forming the outer wall 11 of this first part 1.
If the head is supplied assembled as illustrated in
Of course, the invention is not limited to the examples which have just been described and numerous changes can be made to these examples without exceeding the scope of the invention.
In particular, the shapes and number of the different pieces described can be different. For example, the ribs and the claws can be of a number different from three.
For a sampling system according to the invention set up in a fixed station in an industrial plant, a location for fixing a head there can be similar to a second part as described with reference to
The device can comprise means for verifying the flow rate of air in the head. These means can make it possible to adjust this flow rate, for example in order to compensate for manufacturing tolerances or operator-fitting tolerances.
In order to maintain a suitable distance between the surface of the culture medium and the screen, dimensions of the head can vary and/or be adjustable. Thus, the head can comprise means of adjustment, for example of the position of the claws and/or of the position of the screen. This suitable distance can be a function of the type of Petri dish and/or of a sought type of micro-organisms. The adjustment is preferably carried out in the factory.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0410514 | Oct 2004 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR05/02455 | 10/6/2005 | WO | 3/8/2007 |
