At the present time, it is recognized in the scientific and pharmaceutical community that the spores of
Bacillus stearothermophilus are the organisms of choice for the validation of moist heat sterilization cycles.
Validation of such cycles is based on biological indicators containing a known count of organisms in order to
determine a lethality factor for a given cycle. Those studies are based on parameters such as the “D” value of
certain organisms and also imply a microbiological testing of these indicators at the end of the cycle in order
to establish a survival rate. The use of prions (infectious proteins) could be inadequate in that their detection and quantification, which is based on animal models, is very difficult. Moreover, these proteins are very difficult to destroy and could present a danger should they accidentally be spread in a plant.
