Chlorhexidine body washes may play a role in infection control, decrease environmental contamination

March 2006

A recent, fascinating report by Vernon et al is currently making the rounds at my medical center, with infection control staff and hospital epidemiologists here debating the merits of mounting a study in our teaching hospitals that further examines the effectiveness of chlorhexidine body washes. The study reported on by the Chicago Antimicrobial Resistance Project was carried out in a 21-bed medical ICU at Rush University Medical Center over a 15-month period from October 2002 to December 2003.

The purpose of the study was to evaluate patient skin decontamination as a means of lowering the overall microbial load in an ICU, and perhaps thereby decreasing the level of environmental contamination and transmission within the unit. The test organism identified for study was vancomycin-resistant enterococci (VRE), selected largely because they are known to be transmitted through the environment in ICUs.

The plan of study was as follows: Three sequential time periods were used, each lasting about four to five months. During the first period, all patients in the medical ICU were bathed daily using soap and water; during the second period, all patients were bathed daily using single-use, no-rinse disposable cloths saturated with 2% chlorhexidine gluconate; during the third and final period, all patients were bathed daily with nonmedicated disposable cloths, identical in every way to the cloths used in the second period, save for the absence of chlorhexidine.

All patients were assessed using rectal swabs on the first day and at least every other day thereafter for the presence of VRE colonization. VRE-colonized patients were further studied using standard area skin swabs from right and left inguinal and antecubital skin, both pre-bath and at intervals post-bath. VRE environmental contamination levels were assessed, as well as levels of VRE carriage on nurses’ hands.

The results were quite striking: The results obtained during the last period, using nonmedicated cloths, were quite comparable to those obtained during the first period, using standard soap and water bathing. During the second period, however, there was a greater than 50% reduction in skin colonization with VRE, a significant decrease in VRE contamination in the environment and on nurses’ hands and – most important of all – a sharp and significant decrease in the incidence of VRE acquisition from 29 colonizations per 1,000 patient-days to 9 per 1,000 patient-days. Also of importance, there were no instances of adverse reactions or untoward effects of chlorhexidine on the patients who were bathed, and no change in the susceptibility of enterococci to chlorhexidine during the study period.

The researchers concluded that not only were chlorhexidine washes safe and effective when used in this way, but that this method of “source control” should be considered as an adjunctive measure to reduce transmission of VRE and possibly other organisms, especially multidrug-resistant organisms of epidemiological importance that colonize the skin.

An accompanying editorial by Peterson and Singh, quaintly subtitled “Rub-a-dub-dub, no need for a tub” asked a number of important questions, but overall seemed genuinely supportive of broader use of “source disinfection” as a new tool in the infection control management of patients with multidrug-resistant organisms. Certainly the researchers in the Chicago Antimicrobial Resistance Project are a knowledgeable and experienced group, and merit close attention on that score alone.

There are still some caveats, however. There seems to be a need for at least one or two further studies that confirm the safety and efficacy of this approach, carried out in other medical centers that encounter elevated levels of VRE transmission. As pointed out by Peterson and Singh, subsequent studies should address the issue of hand hygiene compliance, and how that might – or might not — affect the efficacy of chlorhexidine bathing.

Second, this approach should not be adapted to control other significant organisms (eg, methicillin-resistant Staphylococcus aureus, multidrug-resistant gram-negative bacilli) without further study. VRE is somewhat unique in its propensity to spread through environmental contamination. Other organisms of interest may not share that characteristic, and thus may be less effectively controlled by chlorhexidine bathing.

Finally, there are two issues that should always loom large when considering broader application of an antimicrobial agent, including topical microbicides such as chlorhexidine:

• safety; and
• emergence of resistance.

Safety concerns were sought in the study, and none were found. The study group was quite small, however: 1,787 patients. Although it is reassuring that no safety concerns were identified, the denominator was far too small to identify infrequent adverse events. A number of such events have been identified in the past, however, consisting mostly of cutaneous sensitization. Thus, contact dermatitis and even anaphylaxis have been reported from topical chlorhexidine.

Broader use in infection control should be monitored carefully for such adverse events. Recall that babies were washed with hexachlorophene for many years before it was finally learned that premature infants were particularly susceptible to a spongiform encephalopathy secondary to hexachlorophene washing.

Antimicrobial resistance was also sought in the present study, and not found; again, this should provide only modest reassurance. Strains of Pseudomonas have been shown to develop resistance to chlorhexidine, though it is not clear just how frequently this may occur. Nor is it clear if other bacteria may eventually develop chlorhexidine resistance and how readily.

I am not at all against broader use of this interesting approach to “source control”; however, it should be done cautiously, and with due regard to the potential problems that could be identified as we go forward.

For more information:

• Vernon MO, Hayden MK, Trick WE, et al. Chlorhexidine gluconate to cleanse patients in a medical intensive care unit: the effectiveness of source control to reduce the bioburden of vancomycin-resistant enterococci. Arch Intern Med. 2006;166:306-312.
• Peterson LR, Singh K. Universal patient disinfection as a tool for infection control: rub-a-dub-dub, no need for a tub. Arch Intern Med. 2006;166: 274-276.