ATLANTA-- For controlling infection, handwashing may not be all it's cracked up to be. "Soaps and detergents increase the skin's pH," explained Elaine Larson, RN, PhD, professor of pharmaceutical and therapeutic research at Columbia University School of Nursing in New York City. "As you increase the pH, you reduce the [natural] antibacterial activity on the skin."

Handwashing also dries and damages the skin by lowering its lipid content. That, in turn, increases shedding of skin and the many bacteria that colonize it. "So if you use a plain, nonantibacterial soap 15, 20, or 30 times a day, you'll actually see higher colony counts shedding from the skin after a week," said Dr. Larson, who highlighted these and other shortcomings of accepted hand hygiene practices at the 4th Decennial International Conference on Nosocomial and Healthcare-Associated Infections. Her goal was to raise awareness of these risks and suggest ways to reduce them so practitioners would be less likely to infect patients via hand contact (see sidebar).

SURGICAL SCRUB CAUSES SKIN DAMAGE

Investigators discovered long ago that the traditional surgical hand scrub causes skin damage leading to an 18-fold increase in skin shedding, whereas an alcohol hand rinse has no such effect.[1] Participants in this early research scrubbed their hands with soap and a brush for five minutes or used an alcohol hand rinse for 20 to 60 seconds. The researchers learned that the two hand hygiene methods have equal antimicrobial efficacy.

Skin damage is startlingly prevalent on the hands of health care workers, suggests a recent study of 410 full-time acute care nurses.[2] About 25% of these nurses reported damaged skin on their hands at the time of the study, and more than 85% indicated ever having had such skin damage.

In a logistic regression analysis, skin damage correlated significantly with both the type of soap used and gloving frequency. In some cases, the damage was severe enough to cause cracks, fissures, and bleeding. "Interestingly, chlorhexidine gluconate soap caused the least damage," commented Dr. Larson. "Next came plain soap and then the other antimicrobial soaps." Frequent gloving damages the skin through repeated shearing, she noted.

To assess the effect of skin damage on hand flora, Dr. Larson prospectively studied 40 nurses, half of whom had diagnosed hand irritation and half of whom did not.[3] Each nurse's hand hygiene practices were closely observed for three weeks; in both groups, mean handwashing frequency was 12 to 20 times per working shift (12 hours) and mean gloving frequency was once per hour. Most of the nurses used nonantimicrobial soaps, powdered gloves, and hand lotion.

Those with skin damage were no more likely to have high microbial counts on their hands. However, their hands were twice as prone to colonization with Staphylococcus hominis, which grows especially well on dry skin. This finding reached statistical significance despite the study's small sample size. Nurses with skin damage were also twice as likely to have S aureus, gram-negative bacteria, enterococci, and Candida on their hands, but these differences were not statistically significant.

NO CHANGE IN STAPH RESISTANCE

In the past decade or so, no major change has occurred in the overall rate of methicillin-resistant, coagulase-negative Staphylococcus on the hands of health care workers, according to Dr. Larson. The overall rate in her hand flora study--just under 60% in both groups--is comparable to that found in similar investigations completed since 1986.

The prevalence of tetracycline-resistant, coagulase-negative Staphylococcus on health care workers' hands has actually decreased over time. However, the decline probably occurred only as a result of less frequent tetracycline use, Dr. Larson asserted, and this trend would quickly reverse if clinicians began to prescribe tetracycline more often.

Hand colonization by methicillin-resistant Staphylococcus varies widely by hospital setting, she said. For example, this type of colonization was found in 66% of oncology nurses but only 26% of dermatology nurses in one study at a teaching hospital.[4]

HAND FLORA VARIES BY SETTING

In this study, the type of hand flora also varied by setting; for example, colonization with S aureus was found more often on the hands of dermatology nurses and physicians (31% and 37%, respectively) than on those of oncology nurses and physicians (20% and 15%, respectively) or controls (17%). Gram-negative bacteria, multiple antibiotic-resistant aerobic coryneforms, and yeasts were most likely to be found on the hands of oncology nurses.

"Where you do your clinical practice affects the skin flora that you can then transmit to patients," concluded Dr. Larson. Monitoring hand hygiene, minimizing skin scrubbing and shedding, and other methods of improving skin condition are crucial, she added, to avoid the skin damage that leads to undesirable changes in hand flora.

--Timothy Begany

References
1. Meers PD, Yeo GA. Shedding of bacteria and skin squames after handwashing. J Hyg (Lond). 1978;81:99-105.
2. Larson E, Friedman C, Cohran J, et al. Prevalence and correlates of skin damage on the hands of nurses. Heart Lung. 1997;26:404-412.
3. Larson EL, Hughes CA, Pyrek JD, et al. Changes in bacterial flora associated with skin damage on hands of health care personnel. Am J Infect Control. 1998;26:513-521.
4. Horn WA, Larson EL, McGinley KJ, Leyden JJ. Microbial flora on the hands of health care personnel: differences in composition and antibacterial resistance. Infect Control Hosp Epidemiol. 1988;9:189-193.

 

Reducing the Risk of Transmission

How can practitioners change their hand hygiene to minimize microbial transmission to patients? Ban the use of artificial fingernails by health care workers, for starters. "Artificial fingernails have no place in health care," declared Dr. Larson. "And I think we're being wimpy if we don't put that in our policies." Artificial nails, she pointed out, are associated with higher microbial counts and growth of gram-negative bacteria on the hands before and after handwashing. Of course, frequent handwashing will always be crucial. However, practitioners should stick to mild hand cleansers to limit skin damage. In a recent pilot study of 16 neonatal intensive care unit nurses, for example, Dr. Larson reported significantly improved skin condition at four weeks among those who washed their hands with a mild soap and alcohol rinse as compared with those who used a chlorhexidine gluconate (CHG) antiseptic wash.[1] Handwashing and gloving frequency, as well as microbial counts on the hands at baseline, two, and four weeks, were the same for both groups. Hand lotions are important because they reduce dehydration and skin damage. "They may even prevent cross-infection by improving the skin's barrier properties and reducing skin shedding," added Dr. Larson. However, some lotions can neutralize the antimicrobial effect of CHG hand cleansers. To avoid this, clinicians can either switch to another antimicrobial cleanser or plain soap, or choose a hand lotion that doesn't neutralize CHG. --Timothy Begany

Reference 1. Larson E, Silberger M, Jakob K, et al. Assessment of alternative hand hygiene regimens to improve skin health among neonatal intensive care nurses. Heart Lung. 2000;29:136-142.