Abstract:
The present invention is directed to a cap for a microbiological specimen collection tube. The cap includes a hollow space to collect any aerosols that may be generated during the process of specimen collection, transport and incubation. The hollow space defines an aerosol collection chamber. The invention also provides kits for collection of microbiological specimens and methods for their use.

Description:
FIELD OF INVENTION  
         [0001]    The present invention relates to microbiological swabs used to collect a culture from a patient and methods of processing the culture.  
         BACKGROUND OF THE INVENTION  
         [0002]    Microbiological swabs are used to collect a specimen from a patient. The swab typically comprises an absorbent tip at one end of a shaft or stem. The other end may be fixed to a stopper or cap. After the specimen is collected, the absorbent end of the swab is placed in a plastic tube having a closed end. The stopper or cap fits onto the open end of the tube to seal the tube. The tube typically includes an amount of a transport medium to allow any organism collected on the swab tip to multiply so that they can be detected at a diagnostic laboratory.  
           [0003]    There are many different variations of specimen collection and transport kits available. U.S. Pat. No. 3,450,129 discloses a collection and transport device that comprises a flexible outer tube and a frangible ampoule containing a culture medium. After the specimen is collected the frangible ampoule is broken and then a cap is placed over the open end of the tube to seal the tube for transport.  
           [0004]    U.S. Pat. No. 4,311,792 discloses a collection kit which comprises a flexible wire swab which has an elongated stem. The swab fits into a plastic tube. A tubular plastic cap telescopes snugly over the cap. The cap has a reduced diameter tubular neck which telescopically receives the end of the swab. In this was the effective length of the swab can be adjusted to collect a culture from a long body passage.  
           [0005]    Another specimen collection package is disclosed in U.S. Pat. No. 4,749,655. The package comprises a tube, a cap adapted to close the tube, a swabbing device within the tube, a culture sustaining media within the tube and a carbon fiber pledget to help preserve the viability of microorganisms obtained by use of the swab.  
           [0006]    U.S. Pat. No. 4,720,017 discloses a double-ended stopper for a collection tube. The male end of the stopper is used to seal the tube and keep the interior sterile before use. A separate swab is used to take a specimen and is then inserted about ¾ of the way into the tube. The protruding end is broken at a pre-scored point by bending the shaft against the side of the tube. When the female end of the stopper is then placed in the tube, internal gripping means grasp the broken end of the shaft and force the swab down into the tube into contact with a culture medium and at the same time the open end of the tube is sealed.  
           [0007]    Thus, many specimen collection and transport devices have been developed to maintain the viability of the culture and to prevent contamination of the culture during transport to a diagnostic laboratory. However, none of these devices address the problem of the potential danger to a subsequent handler of being infected by the organisms contained in the culture.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention addresses the problem of health hazards for laboratory workers handling microbiological swab specimens that have been transported to the laboratory.  
           [0009]    Conventional caps for specimen collection tubes are adapted to fit tightly in order to prevent drying out of the culture and to maintain the viability of the microorganisms obtained by specimen collection as well as to prevent contamination of the culture from the exterior. As a consequence, when the cap is removed, microbiological particles can be sprayed as an aerosol, due to the “bouncing” effect. The effect can result in the contamination of laboratory surfaces and personnel with viruses or bacteria. The aerosol effect is particularly pronounced when gases are produced in the tube due to microbiological fermentation.  
           [0010]    An object of one aspect of the present invention is to provide a cap for a microbiological swab collection and transport device that reduces the potential for infection of laboratory personnel due to the generation of aerosols when the cap is removed.  
           [0011]    According to one aspect of the invention, there is provided a cap for a specimen collection and transport system. The cap comprises i) a plug portion that has a head adapted to fit snugly into the open end of the culture tube to seal it for transportation and ii) a skirt portion extending from the plug portion. The skirt portion comprises an inner cylindrical wall and an outer cylindrical wall joined to define an aerosol collection chamber  
           [0012]    In another aspect of the invention, a specimen kit for collecting and transporting a microbiological sample is provided. The specimen kit comprises:  
           [0013]    i) a culture tube;  
           [0014]    ii) a swab having a shaft and an absorbent tip; and  
           [0015]    iii) a cap, said cap having a plug portion and a skirt portion wherein the skirt portion comprises an aerosol collection chamber.  
           [0016]    The cap is axially moveable on the tube from a sealing position is which the head of the plug portion fits snugly into the open end of the tube to a venting position in which the aerosol collection chamber is in fluid communication with the interior of the tube.  
           [0017]    In another aspect of the invention, a cap is provided that comprises an internal groove formed by a double wall along at least part of the longitudinal perimeter of the cap. In this type of cap, the aerosol collection chamber is formed in a space above the double walled groove. The inner surface of the double wall may include threads which can interact with grooves on the outer perimeter of the collection tube or vice versa.  
           [0018]    In yet another aspect, the present invention provides a microbiological specimen collection kit comprising a cap as defined above and a specimen collection tube adapted to be sealed by said cap. The microbiological specimen collection kit also comprises a swab and preferably further comprises a growth medium. The microbiological specimen collection kit may be provided in sterile packaging.  
           [0019]    In a further aspect, a method of collecting a microbiological specimen for analysis is provided. The method comprises swabbing a surface, inserting the swab into a microbiological specimen kit as defined above, transporting and incubating the swab and then removing the swab from the collection tube for analysis by releasing the seal of the cap and allowing the air pressure to equalize before removing the cap. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    Preferred embodiments of the invention are illustrated in the accompanying drawings in which like numbers denote like elements and in which:  
         [0021]    [0021]FIG. 1A is a perspective view of a specimen kit of one embodiment of the present invention;  
         [0022]    [0022]FIG. 1B is a perspective view of a collection cap for the specimen kit illustrated in FIG. 1;  
         [0023]    [0023]FIG. 1C is a perpective view of a culture tube for the specimen collection kit of FIG. 1;  
         [0024]    [0024]FIG. 2 is a sectional view through a specimen kit of the embodiment shown in FIG. 1;  
         [0025]    [0025]FIG. 3A illustrates another embodiment of a specimen collection kit according to the present invention; and  
         [0026]    [0026]FIG. 3B is a sectional view through the cap of the specimen collection kit shown in FIG. 3A. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0027]    One embodiment of a specimen collection device according to the present invention is shown in FIG. 1A. The device  10  comprises a culture tube  12  and a cap  14 . The cap  14  and tube  12  are shown in more detail in FIGS. 1B and 1C.  
         [0028]    The cap  14  comprises a generally cylindrical plug portion  16  that includes a head  18  that seals the tube  12 . The cap  14  also includes an integral skirt portion  24  which extends from the generally cylindrical plug portion  16 . The skirt portion  24  comprises an outer cylindrical wall  26  joined to an inner cylindrical wall  28 . The inner wall  28  is spaced from the outer wall  26  to define an aerosol collection chamber  30 . the cylindrical skirt may be biased inwardly to tightly grip the sides of the collection tube. Alternatively, a thread and groove system may be provided so that the cap can be screwed onto the tube.  
         [0029]    The culture tube  12  typically has a closed end  32  and a neck  34  with an open end  36 . The head  18  of the plug portion  16  fits snugly into the open end  36  to provide an airtight seal on the tube. The culture tube can be modified in ways known in the art to provide a ready source of a desired culture medium.  
         [0030]    The cap of the present invention may be provided in combination with a culture tube as shown in the drawings. It is also clearly apparent that the cap can be provided alone for use with standard specimen containers.  
         [0031]    In the embodiment shown in FIG. 2, it can be seen that the diameter of the inner cylindrical wall  28  is selected so that the inner wall slidably engages the outer surface  38  of the culture tube  12 . The cap can move from a sealed position to a venting position. In the sealed position, the head  18  of the plug portion  16  fits snugly into the open end  36  of the tube. In the venting position (not shown), the plug has been released and the inner wall of the skirt portion has been moved up on the tube to a position where the cap is still covering the opening of the tube and there is communication between the interior of the tube and the aerosol collection chamber.  
         [0032]    A sterile swab for specimen collection is optionally provided as an attachment to the cap or it can be provided separately. In a preferred embodiment, the plug portion  16  includes a swab channel  40  that receives the upper end  42  of the shaft of a swab  44 .  
         [0033]    In use, after the sample has been collected and transported to a laboratory for analysis, the seal on the tube is released and any aerosol that is generated due to the build-up of gases in the tube or release of a vacuum is caught in the aerosol collection chamber before the cap is completely removed. This prevents aerosols from being sprayed into the environment.  
         [0034]    In another embodiment shown in FIG. 3, a cap  50  is provided which has a receptacle  52  for holding a swab handle  54 . The swab-holding receptacle  52  is formed in the end part of the cap. The cap may be provided with the swab handle secured in position or the cap may be provided so that the user inserts the swab into place. The cap includes an elongate aerosol chamber  56  which is adapted to communicate with the open end  58  of a collection tube  60 . The cap also includes a circular groove  62  which accepts the circular wall  64  of at the open end  58  of the collection tube. In one embodiment, the fit of the circular wall of the collection tube into the groove of the cap is sufficiently tight to hold the cap in position on the tube. In another embodiment, threads on the inside of the cap interact with grooves on the outer surface of the collection tube and the cap can be screwed into a tight fit.  
         [0035]    The collection tube may have a neck portion  70  as shown in FIG. 3. The neck portion is adapted to fit inside the circular groove in the cap. Alternatively, the diameter of the cap circular groove is adapted to accept the open end of any standard collection tube.  
         [0036]    When the cap is positioned over the tube, the hollow aerosol collection chamber  56  inside the cap allows for an equalization of air pressure. This reduces the “bouncing effect” and minimizes the formation of aerosols.  
         [0037]    The equalization of pressure is beneficial both before and after the specimen is collected. Before use, when the cap is removed there is no vacuum so air-borne contaminants are not pulled into the tube. When a microbial population has been growing inside the tube, there may be the generation of gases. In the present invention, when the cap is then removed there is a reduced aerosol formation since the gases can equalize in the aerosol collection chamber. This results in a reduced risk of infection by inhalation by a laboratory worker and also reduces the risk of cross-contamination between cultures and contamination of laboratory surfaces.  
         [0038]    In a preferred embodiment the cap is provided with the swab attached. The cap and tube are preferably provided in sterile packaging.  
         [0039]    In use, a specimen is collected and transported to the laboratory in a specimen kit according to the present invention. The cap of the present invention collects aerosol generated during the process and prevent unnecessary contamination of laboratory workers and surfaces.  
         [0040]    In one embodiment, the cap is in the sealed position with the head of the plug portion firmly engaged in the open end of the tube. A laboratory worker releases the plug and slides up the cap. Any aerosols that are generated when the plug is released will be trapped in the skirt portion and infectious air particles will be collected into the aerosol collection chamber. This prevents the aerosols from being transmitted into the air and potentially contaminating laboratory surfaces that can result in the spread of infectious agents to laboratory workers. The unique cap of the present invention is also particularly useful in preventing the inhalation of respiratory pathogens by a laboratory worker.  
         [0041]    In another embodiment (shown in FIG. 3) the gases are equalized between the tube and the cap when the tube is gradually removed from the groove in the cap. Any aerosol particles that are formed will be collected on the interior surfaces of the cap.  
         [0042]    The cap and specimen kit provided in accordance herewith are readily and economically manufactured by mass production techniques such as conventional molding procedures. The various parts of the kit can be assembled with little effort.  
         [0043]    While preferred embodiments of the devices have been described herein in detail, the invention is not limited to the specific apparatus and changes may be made without departing from the scope of the invention.