Mar 062015

Throwing the Baby out with the (Chlorhexidine) Bathwater?
New Data on Disinfectant Baths

By Lekshmi Santhosh, MD

As a critical care community, we’ve been forever searching for a magic bullet to eradicate healthcare-acquired infections. So when the pair of 2013 NEJM trials on daily chlorhexidine bathing showed statistically significant reductions on the incidence of hospital-acquired infections, ICUs across the country started implementing daily chlorhexidine bathing, hoping that it would move the needle on local infection rates.

But a new study in JAMA suggests that we may have to reconsider the effectiveness of this practice. In contrast to the prior NEJM articles, this randomized-controlled trial showed that daily chlorhexidine bathing did not significantly reduce healthcare-acquired infections. Similarly, this CHEST article showed that applying oral chlorhexidine pre-intubation did not prevent ventilator-associated pneumonias.

CDC recommends “considering” daily chlorhexidine bathing to prevent CLABSIs and MRSA infections, and the Infectious Disease Society of America gives daily chlorhexidine bathing a Class II recommendation. We are still awaiting cost-effectiveness data to support daily chlorhexidine bathing, but ICUs across the country have already invested thousands of dollars and nurses are spending up to approximately an hour a day on chlorhexidine baths. Is it worth it?

A Closer Look at Vanderbilt’s Chlorhexidine Bathing Study

Investigators at Vanderbilt University (Nashville, TN) performed a randomized controlled trial of their ICU patients from 2012-2013, randomizing the patients to daily chlorhexidine baths versus non-antimicrobial baths. There was also a crossover component of the study where each participating ICU crossed over to the other form of bathing after a pre-prescribed time period (10 weeks followed by a two-week washout period). The study was not blinded due to the different appearance and odor of the cloths. The only patients excluded were ones with known allergies to chlorhexidine or patients admitted with primary dermatologic issues (e.g. burn patients or SJS/TEN patients).

In total, 9,340 patients were ultimately randomized to either chlorhexidine baths versus control baths, and patient demographics were well-balanced between the two groups. As randomized trials go, that's a large n -- bigger than the multicenter Climo study but only a fraction of the size of Huang et al.

As stated, there were no significant differences in healthcare-associated infections between groups.

Perhaps more surprising than chlorhexidine's lack of efficacy were the ultra-low healthcare-associated infection rates in the Vanderbilt ICUs – they noted only 55 infections in the chlorhexidine group over the year as compared to 60 infections in the control group over the same time period. The majority of these infections were catheter-associated UTIs and there were only 8 CLABSIs and 29 cases of C. difficile infection between the two groups. The investigators found no significant differences between the two groups on pre-specified primary and secondary outcomes including incidence of CLABSIs, rates of blood culture contamination, cultures positive for MDR organisms, ICU length of stay, overall length of stay, or in-hospital mortality.

Study Limitations and Perspectives

Of course, critics have cited the study's limitations: this was a single-center unblinded study, with a composite end-point of all health-care associated infections (rather than just CLABSIs, where the biological plausibility for chlorhexidine’s role infection prevention is the highest). Moreover, active infection surveillance was not done and adherence to chlorhexidine bathing was not prospectively monitored. But what truly makes us question this study’s generalizability is the overall low rate of infections seen. In contrast, the prior NEJM Climo study included a fair number of bone marrow transplant patients and did active microbiology surveillance screening, which might have contributed to the higher infection rates seen in that study. But you may remember how the blogosphere responded to the initially erroneous statistics in that paper.

At the end of the day, should your hospital’s ICUs scrap their daily chlorhexidine bathing policies and save the hospitals some money? Not so fast, warns Dr. Catherine Liu, Medical Director of UCSF Medical Center’s Hospital Epidemiology and Infection Control. “For any infection control intervention, one size does not fit all. You have to look at your local microbiology and your institution’s unique issues and you have to think about these interventions in the context of your hospital.” The higher an institution's infection rates at baseline, the more likely any given intervention will make a measurable impact -- with the converse also true at institutions with low infection rates.

takeawayClinical Takeaway: This single-center randomized-controlled crossover trial of Vanderbilt ICUs showed that daily chlorhexidine bathing did not impact healthcare-associated infection rates, however, the study had limitations and local microbiology patterns and practices should be considered.

Noto MJ, Domenico HJ, Byrne DW, et al. Chlorhexidine Bathing and Health Care–Associated Infections: A Randomized Clinical Trial. JAMA. 2015;313(4):369-378. doi:10.1001/jama.2014.18400.

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Chlorhexidine baths in ICU don’t prevent infections in large trial