Biological Indicator (BIs) contain high number, generally 103 – 106, of bacterial endospores that are highly resistant to the sterilization process for which they are designed. It is most accepted means of monitoring sterilization because they assess the sterilization process directly by killing known highly resistant microorganisms (e.g. Geobacillus or Bacillus species). Therefore, if they are destroyed during sterilization, it is assumed that all other life forms are also destroyed which indicates sterilization have taken place completely. TM offer Biological indicator in two forms - Strips or in pre-packaged vials (Ampoules). This biological indicator of sterilization success is a good one and should be done every time you autoclave.
Biological indicator provide the only direct way to measure how lethal a sterilization process was. BI’s are placed in a fully loaded sterilizer and processed with the load.