Self-contained biological indicator
A SCBI useful in ambient air pressure systems is disclosed. The SCBI includes a body which serves as the culture tube, a glass media ampoule, an inoculated stainless steel disc positioned on the top of the glass media ampoule so that the spores are close to the top/opening of the SCBI, filter paper on the top of the body and overlying the disc, and a cap.
1. A method of determining the accuracy of a sterilization or decontamination process in an ambient air isolator comprising the steps of:
placing a self-contained biological indicator (SCBI) in said ambient air isolator in an open position wherein a sterilant gas will enter said SCBI;
said SCBI comprising a body adapted to serve as a culture tube, said body having a cylindrical side wall which does not contain any recessed areas, a bottom wall at one end of the cylindrical side wall closing the body, a collar at the other end of the cylindrical side wall extending outwardly from the cylindrical side wall having an open end having an interior diameter greater than an interior diameter of the cylindrical side wall and adapted to receive a cap, said collar including a plurality of inwardly extending ribs; a cap adapted to engage said body in an open position and a closed position, said cap including a top wall and a cylindrical side wall adapted to engage said collar of said body, said cylindrical side wall including a plurality of apertures; a rupturable glass ampoule including a growth media in said body; a stainless steel disc inoculated with spores on top of said glass ampoule and adjacent said plurality of ribs; and a filter paper covering said stainless steel disc;
subjecting said isolator to said sterilant gas;
removing said SCBI from said isolator and closing said SCBI;
rupturing said glass ampoule in said closed SCBI to release said growth media to said body of said SCBI, wherein said stainless steel disc is adapted to drop down into said cylindrical side wall of said body to contact said inoculated spores with said growth media; and
determining the accuracy of said sterilization process or said decontamination process.
2. A method according to claim 1 wherein said sterilant gas is selected from the group consisting of hydrogen peroxide gas, chlorine dioxide gas and nitrogen dioxide gas.
3. A method according to claim 1 wherein said plurality of inwardly extending ribs extend the horizontal length of said collar and are substantially even with the inside wall of said cylindrical side wall of said body.
4. A method according to claim 3 wherein said plurality of ribs comprise twelve ribs.
5. A method according to claim 4 wherein said plurality of ribs are adapted to allow air flow of a sterilant down the side of said body towards the bottom of said body.
6. A method according to claim 1 wherein said growth media is a formulated soybean casein digest culture medium.
7. A method according to claim 1 wherein said plurality of apertures of said cylindrical side wall of said cap comprise six to eight apertures.
8. A method according to claim 1 wherein said cap includes an annular groove on the inside of said cylindrical side wall and said collar of said body includes upper and lower annular protrusions adapted to engage said annular groove to hold said cap in open and closed positions.