Biological indicator for use with vaporous microbial deactivating agents and method for making same

Abstract

A biological indicator and method of making same. The biological indicator includes a carrier having a recess formed therein in order to restrict movement of an inoculum deposited onto the carrier. The inoculum includes microorganisms (e.g., bacterial spores) suspended in a suspension medium. The microorganisms are prepared by removing extraneous material and subjecting the microorganisms to sonication to break up agglomerations. The suspension medium includes a wetting agent to reduce surface tension, thereby facilitating flow of the suspension medium to prevent stacking of microorganisms on the surface of the carrier, and to allow the inoculum to more evenly “plate out” on carrier surfaces. The carrier, with inoculum deposited thereon, is enclosed in an envelope made of a material permeable to a vaporous deactivating agent (e.g., vaporized hydrogen peroxide, ozone, chlorine dioxide, ethylene oxide, etc.), thereby facilitating exposure to the vaporous deactivating agent.

1 . A biological indicator for determining the efficacy of a microbial deactivation process used to deactivate items by exposing said items to a vaporous deactivating agent, said biological indicator comprising:
 a carrier having a recess formed therein; and   an inoculum including microorganisms suspended in a suspension medium, wherein the inoculum is deposited in the recess.   
     
     
         2 . A biological indicator as defined in  claim 1 , wherein said recess is defined by a bottom surface and sloping side walls that surround the bottom surface and slope away therefrom. 
     
     
         3 . A biological indicator as defined in  claim 1 , wherein said microorganisms include at least one of the following: bacterial spores, bacteria, fungi, viruses, or a combination thereof. 
     
     
         4 . A biological indicator as defined in  claim 1 , wherein said biological indicator further comprises an envelope for enclosing said carrier having said inoculum deposited thereon. 
     
     
         5 . A biological indicator as defined in  claim 4 , wherein said envelope is formed of a material that is permeable to said vaporous deactivating agent and generally impermeable to said microorganisms. 
     
     
         6 . A biological indicator as defined in  claim 5 , wherein said material comprises spun-bonded olefin. 
     
     
         7 . A biological indicator as defined in  claim 1 , wherein said suspension medium includes a wetting agent. 
     
     
         8 . A biological indicator as defined in  claim 7 , wherein said wetting agent is a surfactant compatible with said vaporous deactivating agent. 
     
     
         9 . A biological indicator as defined in  claim 1 , wherein said suspension medium includes an alcohol. 
     
     
         10 . A biological indicator as defined in  claim 1 , wherein said carrier is formed of a polymeric material. 
     
     
         11 . A biological indicator as defined in  claim 10 , wherein said polymeric material includes at least one of the following: polypropylene, polyethylene, polyvinyl-carbonate, polyvinyl styrene, polyvinyl chlorine, polyethylene terephtlialate, nylon, epoxy, or a mixture of polymeric materials. 
     
     
         12 . A biological indicator as defined in  claim 1 , wherein said carrier is formed of a metal. 
     
     
         13 . A biological indicator as defined in  claim 12 , wherein said carrier includes at least one of: aluminum or stainless steel. 
     
     
         14 . A biological indicator as defined in  claim 1 , wherein said carrier is formed of a ceramic. 
     
     
         15 . A biological indicator as defined in  claim 1 , wherein said vaporous deactivating agent is vaporized hydrogen peroxide. 
     
     
         16 . A method of making a biological indicator comprised of a carrier and an inoculum including microorganisms suspended in a suspension medium, the biological indicator determining the efficacy of a deactivation process used to deactivate articles by exposing said articles to a vaporous deactivating agent, said method comprising the steps of:
 cleaning the carrier using a cleaning agent including a detergent;   removing extraneous material from said microorganisms;   exposing said microorganisms to ultrasonic vibrations to break up agglomerations of said microorganisms;   suspending said microorganisms in the suspension medium to form the inoculum; and   depositing said inoculum onto said carrier.   
     
     
         17 . A method of making a biological indicator as defined in  claim 16 , wherein said step of removing extraneous material from said microorganisms includes washing said microorganisms. 
     
     
         18 . A method of making a biological indicator as defined in  claim 16 , wherein said suspension medium includes a wetting agent. 
     
     
         19 . A method of making a biological indicator as defined in  claim 18 , wherein said wetting agent is a surfactant compatible with said vaporous deactivating agent. 
     
     
         20 . A method of making a biological indicator as defined in  claim 16 , wherein said suspension medium includes an alcohol. 
     
     
         21 . A method of making a biological indicator as defined in  claim 16 , wherein said method further comprises:
 enclosing said carrier having inoculum deposited thereon in an envelope made of a material permeable to said vaporous deactivating agent and generally impermeable to said microorganisms.   
     
     
         22 . A method of making a biological indicator as defined in  claim 21 , wherein said material includes a spun-bonded olefin. 
     
     
         23 . A method of making a biological indicator as defined in  claim 16 , wherein said method further comprises the step of:
 rinsing said carrier with a rinsing solution including an alcohol, prior to depositing said inoculum thereon.   
     
     
         24 . A method of making a biological indicator as defined in  claim 16 , wherein said microorganisms include at least one of the following: bacterial spores, bacteria, fungi, viruses, or a combination thereof. 
     
     
         25 . A method of making a biological indicator as defined in  claim 1 , wherein said vaporous deactivating agent includes: vaporized hydrogen peroxide, ozone, chlorine dioxide, or ethylene oxide.