Ethylene oxide resistance of micro-organisms in dust compared with the resistance of Bacillus subtilis spores.

Abstract

The resistance of standardized spore preparations of Bacillus stearothermophilus and Bacillus subtilis to industrial ethylene oxide sterilization procedures was compared. Moreover, the resistance of the most resistant preparation was compared with that of micro‐organisms in dust and dirt. The experiments demonstrated the importance of the water content to the ethylene oxide resistance of “test pieces” intended for the control of the microbiological effect of sterilization procedures. It was demonstrated also that micro‐organisms in dust and dirt may possess an ethylene oxide resistance in the same range as that possessed by B. subtilis spores in the vacuum‐dried routine “test pieces” of Statens Seruminstitut, Copenhagen. Inactivation curves representing the subtilis strain and some of the micro‐organisms which had survived the industrial sterilization procedures revealed that the decisive factor in the inactivation was the water content inside the micro‐organisms or in their immediate vicinity.