Resistance of Micro‐organisms to Inactivation by Gaseous Ethylene Oxide

摘要

A simple method for the exposure of micro‐organisms to ethylene oxide on membrane filters in a modified desiccator has been devised and used to study microbial resistance to the gaseous sterilant and the term ‘R‐value’ is suggested to express this. The resistance of many known species and isolates has been assessed and compared. Several species ofBacilluswere isolated from natural habitats and their spores were found to be more resistant than the strain ofBacillus subtilisvar.niger(NCTC 10073) frequently used to monitor ethylene oxide sterilization. However, endospores of some bacterial species exhibited little resistance. Fungal spores and vegetative bacteria exhibited low resistance to the sterilant except after drying in organic material when they appeared more resistant than spores ofB. subtilisvar.niger.It was concluded that resistance to ethylene oxide did not correlate with resistance to heat, irradiation or other chemical disinfectants, or to the existence in the endospore for