Patent Publication Number: US-8541196-B2

Title: Method for activating a self-contained biological indicator

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/137,591, filed Jun. 12, 2008, now U.S. Pat. No. 8,173,418, which is hereby fully incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to self-contained biological indicators for evaluating the efficacy of a sterilization process, and more particularly, to a device for activating a self-contained biological indicator. 
     BACKGROUND OF THE INVENTION 
     Sterilization is a process conducted in a specially designed chamber or sterilizer that results in a complete eradication of all viable microorganisms. Sterilization techniques have evolved over time from the traditional methods employing saturated steam at elevated temperature and ethylene oxide gases to more modem techniques, such as those employing liquid, vapor and plasma. Regardless of the technique utilized, the effectiveness of the applied sterilization process must be evaluated especially when sterilizing instruments and devices invasive to the human body. 
     Several methods are currently available for evaluating the effectiveness of a sterilization process. In some applications, chemical indicators are placed in the sterilization process to verify that the sterilizing medium was present in the correct concentration during the sterilization process. In other applications, process indicators are used to determine if the sterilizing medium was present in the correct concentration for the proper amount of time. Still other applications use biological indicators to determine if the sterilizing medium was sufficient to deactivate a predetermined number of microorganisms on a test strip or contained in the biological indicator. 
     The biological indicator is typically an absorbent paper strip that contains a predetermined number of microorganisms. The biological indicator is exposed to the sterilizing medium during the sterilization process. At the conclusion of the sterilization process, the biological indicator is placed into a vial containing a growth-promoting medium, i.e., nutrients that aid in the growth of the microorganism. If there are any viable microorganisms on the paper strip that survived the sterilization process, these microorganisms will grow and produce a color change in the growth-promoting medium when properly incubated. The sterilization process is determined to be successful if there is no color change in the growth-promoting medium. In one embodiment, the biological indicator and the growth-promoting medium are disposed in a common housing. The combination of biological indicator and the growth-promoting medium in a common housing is often called a “self-contained biological indicator” (SCBI). 
     Self-contained biological indicators are generally comprised of a tubular housing having an open end and a closed end. A vial containing a growth-promoting medium is disposed in the housing. A source of microorganisms is also disposed in the housing. The source of microorganisms is typically an absorbent paper strip that has been impregnated with a pre-determined concentration of viable microorganisms. The microorganisms may also be disposed directly on the exterior surface of the vial. A cap is disposed over the open end of the housing. The cap is operable to move between an open position and a closed position. When the cap is in the open position, the interior of the housing is in fluid communication with the environment. In this respect, a sterilizing medium is able to flow into the interior of the housing and contact the source of microorganisms during the sterilization process. The self-contained biological indicator is removed from the chamber of the sterilizer at the end of the process. The cap is then moved to a closed position wherein the interior of the housing is fluidly isolated from the environment. Once sealed, the source of microorganisms is exposed to the growth-promoting medium by fracturing or breaking the vial containing the growth-promoting medium. The SCBI is then incubated at a predetermined temperature for a predetermined duration. At the end of the incubation period, the indicator is evaluated either visually or with a detector to determine whether any microorganisms survived the sterilization process. 
     As described above, the source of microorganisms is exposed to the growth-promoting medium. In order to expose the source of microorganisms to the growth-promoting medium, the vial must be fractured by the user. Presently, the user must exert a significant amount of force to the housing of the biological indicator to fracture the vial dispose therein. In some instances, the user may use a blunt instrument, e.g., a hammer, to fracture the vial. As a result, significant damage may occur to the biological indicator if excessive force is used. In this respect, present devices are complicated and may require multiple operations to seal and activate the biological indicator. 
     The present invention provides a device wherein a self-contained biological indicator for determining the efficacy of a sterilization process can be activated. 
     SUMMARY OF THE INVENTION 
     In accordance with a preferred embodiment of the present invention, there is provided a device for activating a self-contained biological indicator. The biological indicator includes a casing, an ampule having a growth-promoting medium disposed therein and microorganisms. The ampule and microorganisms are disposed within the casing. The device is comprised of a first lever arm having a cavity formed therein. The cavity is dimensioned to receive a biological indicator. A second lever arm has a protrusion extending from a surface thereof and is moveable relative to the first lever arm to deform a casing of the biological indicator thereby fracturing an ampule within the casing and exposing microorganisms within the casing to a growth-promoting medium disposed in the ampule. 
     In accordance with yet another embodiment of the present invention, there is provided a method of activating a self-contained biological indicator in a device. The biological indicator includes a casing, an ampule having a growth-promoting medium disposed therein and microorganisms. The ampule and microorganisms are disposed within the casing. The method is comprised of the steps of: 
     a) moving a device comprised of a first lever arm and a second lever arm to an open position, wherein the first lever arm is moveable relative to the second lever arm; 
     b) locating a biological indicator in a cavity located in the first lever arm of the device while the device is in the open position; and 
     c) moving the device to a closed position by moving the second lever arm relative to the first lever arm such that a protrusion on the second lever arm fractures an ampule within the biological indicator thereby allowing a growth-promoting medium within the ampule to be exposed to microorganisms disposed in a casing of the biological indicator. 
     An advantage of the present invention is the provision of a device for activating a biological indicator. 
     Another advantage of the present invention is the provision of a device that seals a self-contained biological indicator prior to activating the self-contained biological indicator. 
     Still another advantage of the present invention is the provision of a device, as described above, that requires a simple operation to seal and activate a self-contained biological indicator. 
     Still another advantage of the present invention is the provision of a device, as described above, that is inexpensive to manufacture. 
     Yet another advantage of the present invention is the provision of a device, as described above, that allows hand-held operation. 
     Yet another advantage of the present invention is the provision of a device, as described above, that can be operated with one hand. 
     These and other advantages will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein: 
         FIG. 1  is a perspective view of a device for sealing and activating a self-contained biological indicator according to an embodiment of the present invention, wherein the device is shown in an open position with a biological indicator located outside the device; 
         FIG. 2  is a side plan view of the device and biological indicator shown in  FIG. 1 ; 
         FIG. 3  is a top plan view of the biological indicator shown in  FIG. 2 , wherein the biological indicator is shown in phantom inside the device; 
         FIG. 4  is a side plan view partially in section of the device for sealing and activating a biological indicator, wherein the device is shown in a partially open position with a biological indicator located inside the device; 
         FIG. 5  is a side plan view partially in section of the device shown in  FIG. 4 , wherein the device is shown in a closed position; 
         FIG. 6  is a sectional view taken along lines  6 - 6  of  FIG. 3 ; 
         FIG. 7  is a sectional view of a biological indicator showing a cap of the biological indicator in an unsealed or open position; and 
         FIG. 8  is a sectional view of the biological indicator shown in  FIG. 7 , showing the cap of the biological indicator in a sealed or closed position. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Referring now to the drawings wherein the showings are for the purpose of illustrating an embodiment of the invention only, and not for the purpose of limiting same.  FIGS. 7 and 8  show a typical self-contained biological indicator  50  that is used in connection with device  10 . Broadly stated, biological indicator  50  is comprised of a casing  52 , a cap  72 , an ampule  66  and a microorganism-inoculated element  68 . It should be understood that indicator  50  is merely exemplary of a biological indicator suitable for use in connection with the present invention, and is not intended to limit the scope of the present invention. 
     Casing  52  is a generally cylindrical container having a cylindrical side wall  54 , an open end  56  and a closed end  58 . Casing  52  defines an interior cavity  62  dimensioned to receive ampule  66  and microorganism-inoculated element  68 . A series of tabs  64  extend radially outward from side wall  54  near open end  56 . The material for casing  52  is chosen such that when side wall  54  of casing  52  is subjected to a force, side wall  54  will deform but not fracture. Casing  52  is preferably formed of a translucent, polymer material, such as by way of example and not limitation, polypropylene, polyethylene, polycarbonate, polyvinyl carbonate, polyvinyl styrene, polyvinyl acetate, polymethylmethacrylate or any copolymers of the above materials. 
     Ampule  66  is a sealed enclosure formed from a frangible material, such as glass or other suitable materials, that allows ampule  66  to be opened by applying an external force sufficient to fracture or break ampule  66 , as shall be described in greater detail below. It shall be appreciated that ampule  66  may assume shapes that differ from the shape illustrated herein. A growth-promoting medium  88  is disposed within ampule  66 . Growth-promoting medium  88  is well known to those skilled in the art, and therefore shall not be described in detail. Examples of commonly used growth-promoting mediums include, but are not limited to, trypic soy broth and soybean casein digest growth media. 
     In the illustrated embodiment, microorganism-inoculated element  68  is a paper patch inoculated with spores or other microorganisms, as is conventionally known in the art. Microorganism-inoculated element  68  may be attached to the inner surface of casing  52 , but in the embodiment shown, element  68  is affixed to an outer surface of ampule  66 . In an alternative embodiment (not shown), the microorganisms are disposed directly on the exterior surface of ampule  66  or on the interior surface of casing  52 . 
     Cap  72  is generally cup-shaped and includes a cylindrical side wall  74  and an end wall  76 . A ring-shaped boss  82  extends inward from end wall  76 . Boss  82  is centrally located on cap  72 . An annular protrusion  84  extends radially outward from boss  82  near a distal end thereof. An annular groove  78  is formed in side wall  74  near an open end of cap  72 . Annular groove  78  is dimensioned to accept tabs  64  of casing  52 , as best seen in  FIG. 7 . An opening  86  is formed between casing  52  and cap  72 , as best seen in  FIG. 7 , when tabs  64  are disposed in groove  78 . 
     Cap  72  is movable between an unsealed or open position, best seen in  FIG. 7 , and a sealed or closed position, best seen in  FIG. 8 . In the open position, tabs  64  of casing  52  are disposed in annular groove  78  of cap  72 . In this respect cavity  62  of casing  52  is in fluid communication with the exterior of indicator  50  through opening  86 . In the sealed position, boss  82  of cap  72  is disposed in open end  56  of casing  52  such that annular protrusion  84  sealingly engages side wall  54  of casing  52 . In this respect, a seal is formed between cap  72  and casing  52 , thereby isolating cavity  62  from the exterior of indicator  50 . 
       FIG. 1  shows a device  10  for activating a self-contained biological indicator (such as indicator  50  described above) in accordance with an embodiment of the present invention. Device  10  is described herein in connection with the sealing and activation of indicator  50 . However, it is contemplated that device  10  may be used to seal and activate biological indicators of alternative designs. 
     Broadly stated, device  10  is comprised of a first lever arm  20  and a second lever arm  40 . In the illustrated embodiment, a hinge member  30  connects a distal end of first lever arm  20  to a distal end of second lever arm  40  such that second lever arm  40  is rotatable relative to first lever arm  20 . Second lever arm  40  is rotatable such that device  10  is movable between an open position and a closed position, as shall be described in greater detail below. It will be appreciated that first lever arm  20  and second lever arm  40  may be connected with each other by means other than hinge member  30 . For example, first lever arm  20  and second lever arm  40  may be molded such that an integral hinge is formed therebetween. 
     In the embodiment shown, first lever arm  20  is an elongated rectangular member with a top surface  22 . A cavity  28  is formed in top surface  22 , as best seen in  FIG. 1 . Cavity  28  is defined by end surface  32 , side walls  34 ,  36  and bottom surface  37 . Cavity  28  is dimensioned to accept a biological indicator, such as indicator  50  described above. In the illustrated embodiment, a recess  38  is formed proximate one end of cavity  28 , as best seen in  FIG. 1 . Recess  38  is dimensioned to facilitate the removal of indicator  50  from cavity  28 , as shall be described in greater detail below. 
     In the embodiment shown, second lever arm  40  is a generally L-shaped member having an elongated first portion  42  and a shorter second portion  44  that is substantially perpendicular to first portion  42 . A protrusion  46  extends from first portion  42 , as shown in  FIG. 1 . In the embodiment shown, protrusion  46  is a generally triangular-shaped member that extends outward from first portion  42 . Protrusion  46  is located along first portion  42  such that protrusion  46  aligns with cavity  28  when device  10  is in the closed position. 
     A cam member  48  is disposed at a corner where first portion  42  meets second portion  44 . In the embodiment shown, cam member  48  is a generally rectangular element that extends outwardly from first portion  42  and second portion  44 . An engaging surface or edge  48   a  of cam member  48  faces cavity  28 . 
     Device  10  is operable to be moved between the open position, best seen in  FIGS. 1 and 2 , and the closed position, best seen in  FIG. 5 . In the open position, first lever arm  20  and second lever arm  40  are disposed such that cavity  28  in first lever arm  20  is accessible. In the closed position, edge  48   a  of cam member  48  is partially disposed in cavity  28  of first lever arm  20  and protrusion  46  aligns with and extends into cavity  28 , as best seen in  FIG. 5 . In the embodiment shown, first lever arm  20  and second lever arm  40  are substantially parallel when device  10  is in the closed position. 
     Operation of device  10  will now be described in connection with the sealing and activation of a biological indicator (such as indicator  50 ). Indicator  50  is sealed and activated using device  10  following the use of indicator  50  in a sterilizer. In this respect, indicator  50  is placed within a chamber of a sterilizer (not shown) along with objects to be sterilized. Cap  72  of indicator  50  is in the unsealed or open position, as illustrated in  FIG. 7 . During a sterilization cycle, the sterilant fluid (gas or liquid) that is used in the sterilizer flows through opening  86  between cap  72  and casing  52 , and into cavity  62  of casing  52  where the sterilant fluid acts on the microorganism-inoculated element  68 . 
     At the end of the sterilization cycle, indicator  50  is removed from the chamber of the sterilizer. Device  10  is moved to the open position by rotating second lever arm  40  away from first lever arm  20 . Indicator  50  is then placed into cavity  28  of device  10 , as shown in  FIGS. 2 ,  3  and  6 . As described above, cavity  28  of device  10  is dimensioned such that when indicator  50  is disposed in cavity  28 , indicator  50  contacts end surface  32  of cavity  28 , as best seen in  FIG. 4 . Device  10  is moved from the open position to the closed position by rotating second lever arm  40  toward first lever arm  20 . As second lever arm  40  moves toward first lever arm  20 , device  10  moves from the open position, to an intermediate position to a closed position. As device  10  moves from the open position to the intermediate position, edge  48   a  of cam member  48  moves into cavity  28 . Accordingly, indicator  50  is captured between cam member  48  and end surface  32 . Edge  48   a  of cam member  48  initially contacts or engages cap  72  of indicator  50  as first lever arm  20  and second lever arm  40  move towards each other. As second lever arm  40  continues to move toward first lever arm  20 , the distance between edge  48   a  of cam member  48  and end surface  32  decreases thereby causing the distance between cap  72  of indicator  50  and closed end  58  of indicator  50  to decrease. As cap  72  moves toward closed end  58 , a first compressive force is applied to indicator  50  thereby causing cap  72  of indicator  50  to move from the unsealed or open position, best seen in  FIG. 7 , to the sealed or closed position, best seen in  FIG. 8 . Device  10  is in the intermediate position once cap  72  is in the sealed or closed position. In other words, cam member  48  is dimensioned such that when device  10  is in the intermediate position, the distance between engaging surface or edge  48   a  of cam member  48  and end surface  32  is equal to or less than the height of self-contained biological indicator  50  in the sealed or closed position. As a result, indicator  50  is sealed by device  10  when device  10  is in the intermediate position. 
     As second lever arm  40  continues to move relative to first lever arm  20 , device  10  moves from the intermediate position to the closed position. As device  10  moves from the intermediate position to the closed position, protrusion  46  moves toward cavity  28  in first lever arm  20 . Protrusion  46  initially contacts side wall  54  of casing  52 . As second lever arm  40  continues to move toward first lever arm  20 , protrusion  46  exerts a second, compressive force on side wall  54  of casing  52 . Protrusion  46  is dimensioned such that the second, compressive force exerted on side wall  54  of casing  52  causes side wall  54  to deform and apply a compressive force to ampule  66  sufficient to fracture or break ampule  66 , as shown in  FIG. 5 . Device  10  is in the closed position when ampule  66  is fractured by protrusion  46 . As a result, microorganism-inoculated element  68  is exposed to growth-promoting medium  88  within ampule  66 . 
     The sealing of casing  52  and fracturing of ampule  66  basically “activates” indicator  50  by exposing microorganism-inoculated element  68  to medium  88 . Once activated, device  10  is moved to the open position and indicator  50  is removed from device  10 . Recess  32  is dimensioned to allow an operator&#39;s finger to grip closed end  58  of indicator  50 . In this respect, recess  32  is dimensioned to allow an operator to squeeze closed end  58  and cap  72  between a thumb and an opposing finger to aid in the removal of indicator  50  from device  10 . Indicator  50  is then placed in a conventional incubator (not shown) at a temperature and for a time suitable for growing the microorganism in growth-promoting medium  88 . 
     The present invention thus provides a device for quickly and easily activating a self-contained biological indicator  50 . As indicated above, the rotation of second lever arm  40  relative to first lever arm  20  first seals the self-contained biological indicator  50  then fractures ampule  66  disposed in casing  52 . 
     In an alternative embodiment of the present invention (not shown), cam member  48  is omitted from device  10 . In this embodiment, it is contemplated that a user manually seals indicator  50  prior to placing indicator  50  in device  10 . Thereafter, device  10  is moved from an open position to a closed position to fracture ampule  66 , thereby activating indicator  50 . Once activated, device  10  is moved to the open position and indicator  50  is removed from device  10 . 
     The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.