Hygiene of the Skin: When Is Clean Too Clean?

Elaine Larson, Columbia University School of Nursing, New York, New York, USA.

Disclosures

Emerging Infectious Diseases. 2001;7(2) 

In This Article

Does Skin Cleansing Reduce Risk for Infection?

There is a clear temporal relationship between improvement in general levels of cleanliness in society and improved health. Greene[2] used historical and cross-cultural evidence and causal inference to associate personal hygiene with better health. However, the role of personal cleanliness in the control of infectious diseases over the past century is difficult to measure, since other factors have changed at the same time (e.g., improved public services, waste disposal, water supply, commercial food handling, and nutrition)[3].

Studies of personal and domestic hygiene and its relationship to diarrhea in developing countries demonstrate the effectiveness of proper waste disposal, general sanitary conditions, and handwashing[4,5]. However, aside from hand cleansing, specific evidence is lacking to link bathing or general skin cleansing with preventing infections. Part of the difficulty in demonstrating a causal association between general bathing or skin care and gastrointestinal infection is that interventions to reduce diarrheal disease have been multifaceted, often including health education, improved waste disposal, decontaminating the water supply, and general improvement in household sanitation as well as personal hygiene[6,7]. Risk for diarrheal disease has also been linked to the level of parental education[8]. Multiple influences complicate definition of the impact of any single intervention.

In 11 studies reviewed by Keswick et al.[9], use of antimicrobial soaps was associated with substantial reductions in rates of superficial cutaneous infections. Another 15 experimental studies demonstrated a reduction in bacteria on the skin with use of antimicrobial soaps, but none assessed rates of infection as an outcome.

Extensive studies of showering and bathing conducted since the 1960s demonstrated that these activities increase dispersal of skin bacteria into the air and ambient environment[10,11,12], probably through breaking up and spreading of microcolonies on the skin surface and resultant contamination of surrounding squamous cells. These studies prompted a change in practice among surgical personnel, who are now generally discouraged from showering immediately before entering the operating room. Other investigators have shown that the skin microflora varies between persons but is remarkably consistent for each person over time. Even without bathing for many days, the flora remain qualitatively and quantitatively stable[13,14,15].

For surgical or other high-risk patients, showering with antiseptic agents has been tested for its effect on postoperative wound infection rates. Such agents, unlike plain soaps, reduce microbial counts on the skin[16,17,18]. In some studies, antiseptic preoperative showers or baths have been associated with reduced postoperative infection rates, but in others, no differences were observed[19,20,21]. Whole-body washing with chlorhexidine-containing detergent has been shown to reduce infections among neonates[22], but concerns about absorption and safety preclude this as a routine practice. Several studies have demonstrated substantial reductions in rates of acquisition of methicillin-resistant Staphylococcus aureus in surgical patients bathed with a triclosan-containing product[23,24]. Hence, preoperative showering or bathing with an antiseptic may be justifiable in selected patient populations.

Much contemporary evidence for a causal link between handwashing and risk for infection in community settings comes from industrialized countries[5,7,25,26,27]. Although many of these studies may be limited by confounding by other variables, evidence of an important role for handwashing in preventing infections is among the strongest available for any factor studied. Reviews of studies linking handwashing and reduced risk for infection have been recently published[28,29]. The most convincing evidence of the benefits of handwashing for the general public is for prevention of infectious agents found transiently on hands or spread by the fecal-oral route or from the respiratory tract[30]. Plain soaps are considered adequate for this purpose.

Several highly publicized, serious outbreaks from commercially prepared foods have raised questions about food safety and the hygienic practices of food handlers and others in the service professions. Despite public awareness, however, handwashing generally does not meet recommended standards--members of the public wash too infrequently and for short periods of time[31].

These factors have led to suggestions that antimicrobial products should be more universally used, and a myriad of antimicrobial soaps and skin care products have become commercially available. While antimicrobial drug-containing products are superior to plain soaps for reducing both transient pathogens and colonizing flora, widespread use of these agents has raised concerns about the emergence of bacterial strains resistant to antiseptic ingredients such as triclosan[32,33]. Such resistance has been noted in England and Japan[34], and molecular mechanisms for the development of resistance have been proposed[32,35]. Although in some settings exposure to antiseptics has occurred for years without the appearance of resistance, a recent study described mutants of Escherichia coli selected for resistance to one disinfectant that were also multiply-antibiotic resistant[35]. Some evidence indicates that long-term use of topical antimicrobial agents may alter skin flora[36,37]. The question remains whether antimicrobial soaps provide sufficient benefit in reducing transmission of infection without added risk or cost.

Issues regarding hand hygiene practices among health-care professionals have been widely discussed and may be even more complicated than those in the general public. Unless patient care involves invasive procedures or extensive contact with blood and body fluids, current guidelines recommend plain soap for handwashing[38,39]; however, infection rates in adult or neonatal intensive care units or surgery may be further reduced when antiseptic products are used[40,41,42].

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