EFFECT OF MOISTURE ON ETHYLENE OXIDE STERILIZATION

Area of Science:

• Microbiology
• Sterilization science

Background:

• Bacterial cell dehydration significantly impacts their response to sterilization methods.
• Ethylene oxide sterilization efficacy is reduced when bacterial cells are desiccated.

Purpose of the Study:

• To investigate the phenomenon of increased resistance of dehydrated bacterial cells to ethylene oxide sterilization.
• To identify factors influencing this resistance and its reversibility.

Main Methods:

• Desiccation of bacterial cells using vacuum or chemical desiccants.
• Exposure to ethylene oxide to assess sterilization resistance.
• Rehydration studies at various relative humidity levels.
• Moisture content analysis of bacterial cells.

Main Results:

• Dehydrated bacterial cells exhibit significantly increased resistance to ethylene oxide, with resistance levels ranging from 0.001% to 5%.
• Organic matter and vacuum enhance this desiccation-induced resistance.
• Resistance is reversible upon rehydration, though high relative humidity requires several days to restore susceptibility.
• Desiccated cells equilibrated to high RH retain less water than naturally dried cells.

Conclusions:

• Bacterial cell dehydration is a critical factor affecting ethylene oxide sterilization outcomes.
• Understanding desiccation resistance is crucial for optimizing sterilization protocols, especially in the presence of organic matter.
• Reversibility of resistance highlights the importance of moisture content in bacterial cell viability post-sterilization.