抄録
In the current International Organization for Standardization (ISO) document 11138 series describing biological indicators (BIs), the use of multiple types of microorganisms in a single carrier was rejected because the resistance of individual microorganisms may change due to interference from other strains. In order to confirm the validity of this speculation, we compared the resistance (D value) of a single strain of microorganism with that of the same strain in existence with another strain in identical carrier material. Both BIs were exposed to ethylene oxide gas (EOG) sterilization and moist heat sterilization. D value of B. subtilis and that of B. stearothermophilus spores as a single and as one of two coexistent strains was determined. No statistically significant difference (F-test, p<0.05) ofD value between single and multiple strains was observed in either sterilization method, indicating there was no experimental resistance interference and the speculation at the ISO meeting was unfounded.
