ABSTRACT
The principle of using resistant endospores to check the performance of a sterilization process was established by R. Koch. The reproducibility of biological indicator performance is clearly dependent upon the exercise of appropriate storage conditions between manufacture and use. The range of commercially available endospore indicators is wide, with products from several manufacturers available in most Western countries. The influence of vegetative growth conditions on the composition and performance properties of endospores has been covered. In contrast to vegetative cells, bacterial spores unfortunately cannot conveniently be produced in large numbers from chemostats. Spores to be used in biological indicators must possess a level of resistance to the lethal agent in question which is within a relatively narrow specified range. The vast majority of published work on spores as sterilization indicators has been concerned primarily or exclusively with resistance. A variety of B. stearothermophilus strains have been examined as potential biological indicators.
