Biological indicators in strip form or other carriers consist of bacterial spores inoculated onto paper strips or other supports such as rods, threads, or discs, made of various materials including steel, cotton, or fiberglass.
The carrier is usually enclosed in a paper pouch, which must be placed inside the load and subjected to the sterilization cycle, during which the sterilizing agent comes into contact with the spores. For specific applications, the carrier is supplied bare, without a pouch.
At the end of the sterilization process, the carrier must be removed from the pouch and incubated in Soybean Casein Digest Broth (TSB). Any turbidity of the broth indicates bacterial growth and therefore failure of the sterilization process.
With standard TSB, the incubation time is 7 days.
To reduce incubation time, each manufacturer offers optimized culture media equipped with a pH indicator that changes color in the presence of bacterial growth, thus making the procedure much shorter, down to only a few hours of incubation.
The manufacturer validates the reduced incubation time for its own biological indicators in relation to specific sterilization methods.
