GENEVA—An alcohol-based gel may not be the best choice for hand hygiene in health care settings because these gels do not kill microbes well enough, Swiss researchers warn. The group recently assessed the antimicrobial efficacy of 10 alcohol-based hand gels and four alcohol-based hand rinses.[1]

None of the gels measured up to the microbial reduction capability of 60% 2-propanol, the standard reference antiseptic in all European tests of hand hygiene products. The hand rinses were as effective, however.

“Many people in the United States are embarrassed by our study results because most of the hand rubs there are gels,” Didier Pittet, MD, one of the researchers, told RESPIRATORY REVIEWS. However, both alcohol-based hand rinses and gels are better than washing with soap and water, the main form of hand hygiene in the United States, stressed Dr. Pittet, Director of the Infection Control Program at the University of Geneva Hospitals.

A LABORATORY STUDY

Clinical testing is necessary to confirm the study findings, acknowledged Dr. Pittet, because the study took place in a laboratory setting. Researchers tested a total of almost 200 volunteers whose hands had been intentionally contaminated by immersion for five seconds in a fluid that contained Escherichia coli. Microbial levels were then determined by having the volunteers rub their fingertips in a petri dish to obtain a culture.

The volunteers’ hands were then disinfected for 30 seconds with 3 mL of an alcohol-based hand rinse or gel or with the control solution of 60% 2-propanol. “Health care workers never have more than 15 to 30 seconds to de-germ their hands,” Dr. Pittet explained. Repeat cultures were taken by once again having the volunteers rub their fingertips in a petri dish.

As part of the study’s crossover design, all of the hand hygiene products and the reference antiseptic were tested on every volunteer. Ethanol was the active ingredient in most of the hand gels and rinses; a few contained 1- or 2-propanol. The alcohol content of the hand gels ranged from 53% to 70%.

BETTER GELS ARE NEEDED

The gels had the poorest antimicrobial efficacy; they reduced the bacterial count on the volunteers’ hands about half as well as did 60% 2-propanol. In contrast, the hand rinses displayed about the same antimicrobial efficacy as the reference antiseptic.

The gels may have been least effective because they contain glycerol, an additive that may reduce their antimicrobial activity. Moreover, ethanol, the main ingredient in most of the gels, is known to be somewhat less active against bacteria than propanol at equal concentrations.

However, antiseptic gels are desirable in that they do not splash on the user or the floor the way rinses sometimes do. They also reduce skin irritation and dryness associated with water-based hygiene methods. “So, what we all obviously want is for companies to make more effective gels,” Dr. Pittet stated. Gels probably need to contain at least 80% ethanol to match the antimicrobial efficacy of 60% 2-propanol, he estimated. “But even in their current form, I would still recommend them over soap and water,” he said.

—Timothy Begany