NEWS

Soap and water, chlorine- but not alcohol-based products, should reduce anthrax contamination risks, study reveals

By DAVID WILLIAMSON
UNC News Services

CHAPEL HILL -- Old-fashioned hand washing with soap and water significantly reduces the amount of contamination on volunteers’ hands from a form of bacteria comparable to anthrax, a new study shows. A chlorine-based antiseptic product worked about the same and did not require running water.

A waterless foam containing ethyl alcohol and used for disinfecting hands, however, was ineffective in removing spores of the bacteria studied and should not be used for that purpose, researchers say.

A report on the experiments, conducted by medical scientists at the University of North Carolina at Chapel Hill, appears in the March 12 issue of the Journal of the American Medical Association. Chief authors are Dr. David J. Weber and William A. Rutala, professors of medicine at the UNC School of Medicine.

"Given the recent terrorist use of anthrax in the United States, it’s very important for us to be able to give guidance to both health-care workers and emergency medical technicians about what products they can use to decontaminate their skin and patients’ skin," said Weber, also professor of epidemiology at the UNC School of Public Health. "Before the attacks of 2001, almost nobody had studied anthrax for many years, and so there were no real data about hand hygiene agents’ effects on it."

Because it is in the same genus as anthrax, Weber and Rutala chose to work with Bacillus atrophaeus, a bacterium harmless to humans but common in the environment and closely related to its deadly cousin.

"Previous studies back in the ‘30s, ‘40s and ‘50s with other agents showed that Bacillus atrophaeus was slightly more resistant to germicides than anthrax, which is exactly what you’d want for a test organism since if we can kill it, we can kill anthrax," Weber said.

In their tests, researchers first contaminated volunteers’ hands with the harmless microorganism and had them wash their hands for 10 seconds, 30 seconds or 60 seconds with each product. The time between each trial individual volunteers participated in was at least two weeks.

Using microbiological laboratory techniques, scientists determined what happened when subjects washed with simple soap and water, the antiseptic agent chlorhexidine gluconate commonly used in hospitals, a waterless alcohol foam hospitals also employ and a new bleach-impregnated towel.

"Our data suggest that a soap and water hand wash is likely adequate for decontamination of exposed persons," said Rutala, also director of the UNC-based N.C. Statewide Program for Infection Control and Epidemiology.

"Antimicrobial agents, such as chlorhexidine gluconate, did not provide improved elimination of B. atrophaeus spores compared with soap and water," said Rutala. "Alcohol-based hand rubs should not be used because they are ineffective in inactivating or removing spores. When soap and running water are not available in the field, small amounts of water could be carried in rescue vehicles and added to the chlorine-containing towels for hand washing."

If anthrax contamination is a possibility, workers should wear gloves but also wash their hands before and after glove removal, he and Weber recommend.

Twenty-two people in the United States became ill from anthrax in October and November, 2001, including 11 by inhaling it and 11 by skin contact, they wrote. Prior to biological terrorist attacks, human infection came chiefly from contact with infected animals or infected animal products such as wool, hide, hair or bone.

"Bacillus anthracis has been recognized as a likely agent for bioterrorism because the spores are highly stable in the environment, virtually all persons are susceptible, infection can occur as a result of inhalation of spores and considerable morbidity and mortality result from infection," the scientists said.

Co-authors of the paper were researchers Emily Sickbert-Bennett and Maria F. Gergen. Rutala also directs of the Hospital Epidemiology, Occupational Health and Safety Program for the UNC Health Care System.

The N.C. Statewide Program for Infection Control and Epidemiology and the UNC Heath Care System supported the study. The Chlorox Co. and Advanced Sterilization Products contributed bleach-impregnated towels.

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Note: Respectively, Weber and Rutala can be reached at (919) 966-2536 and 843-1397. E-mails: Dweber@unch.unc.edu and brutala@unch.unc.edu

School of Public Health Contact: Lisa Katz, (919) 966-7467
News Services Contact: David Williamson, (919) 962-8596