[The suitability of bioindicators according to DIN 58948 part 4 for monitoring gas-sterilizers (author's transl)].

In the Federal Republic of Germany bioindicators according to DIN 58948, Part 4, are generally used for testing the efficacy of ethylene oxide sterilizers. They are based on spores of Bacillus subtilis dried in sheep-blood on the bottom of a small test tube. As some authors doubted the resistance of these indicators to ethylene oxide especially in comparison with spore soil and spores of Clostridium perfringens, three different test procedures were performed showing that spores of sulfite reducing clostridia (Cl. perfringens included) are less resistant to ethylene oxide than spores of B. subtilis. The results are summarized in tables 1 to 3. They are discussed with regard to literature on the subject with special emphasis to the significance of occlusion of spores in insoluble crystals. It is concluded that spores of B. subtilis are the most suitable test-organisms for monitoring ethylene oxide sterilization and that spore soil cannot be used for this purpose.