This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gilbert, G. L. Articles by Phillips, C. R. Search for Related Content PubMed Articles by Gilbert, G. L. Articles by Phillips, C. R. Agricola Articles by Gilbert, G. L. Articles by Phillips, C. R.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1964 November; 12(6): 496-503
Copyright © 1964 American Society for Microbiology. All Rights Reserved.

Effect of Moisture on Ethylene Oxide Sterilization¹

U.S. Army Biological Laboratories, Fort Detrick, Frederick, Maryland

ABSTRACT

Bacterial cells dehydrated beyond a critical point no longer react uniformly to ethylene oxide sterilization. The percentage of cells resistant to the lethal effect of ethylene oxide after desiccation is often as small as 0.1 to 0.001%. However, 5% resistant cells were observed with one type of microorganism dried in broth. The presence of organic matter increases the percentage of cells that become resistant to ethylene oxide after dehydration. The phenomenon is produced by exposing cells to a vacuum or a chemically desiccated atmosphere. It is not a permanent change, because the resistant cells rapidly become susceptible if wetted with water. On the other hand, mere exposure to a high relative humidity (RH), i.e., 75 to 98%, after desiccation requires 6 and 4 days, respectively, to overcome this resistance. Moisture studies showed that there is less water in bacterial cells that have been desiccated and then equilibrated to successively high RH values up to 100% RH, than in cells that have not been desiccated, but allowed to dry naturally until equilibrated to the same RH values.

¹ A portion of this paper was presented by C. R. Phillips at the symposium on "Recent Developments in the Sterilization of Surgical Materials" organized by the Pharmaceutical Society of Great Britain and Smith & Nephew Research Ltd., and held at the School of Pharmacy, University of London, 11-13 April 1961.