MRSA: Universal Decolonization Beats Screening and Isolation

Jenni Laidman

May 30, 2013

Washing every patient in intensive care units (ICUs) daily with chlorhexidine-impregnated cloths reduced positive cultures of methicillin-resistant Staphylococcus aureus (MRSA) by 37% and reduced bloodstream infection by any pathogen by 44%, according to a study published online May 29 in the New England Journal of Medicine.

Susan S. Huang, MD, MPH, associate professor, infectious disease, University of California, Irvine, School of Medicine, and colleagues compared the effect of 3 methods of infection control in 43 Hospital Corporation of America hospitals. The study included 74 adult ICUs and 74,256 patients.

The study ran in 3 phases, with a 12-month baseline period (from January to December 2009), a 4-month phase in period (from January 1 to April 7, 2010), and an 18-month intervention period (from April 8, 2010, to September 30, 2011).

The researchers randomly assigned participating hospitals to 1 of 3 actions: screening for MRSA followed by isolation of those testing positive, targeted decolonization of MRSA-positive patients and isolation, and universal decolonization of all ICU patients without screening. Patients were decolonized via daily cleansing with chlorhexidine-impregnated cloths and 5 days of twice-daily intranasal mupirocin treatments.

There was no significant difference in the rate of MRSA infections among the 3 groups in the baseline period. However, pairwise comparisons showed that universal decolonization led to a significantly larger decline between baseline and intervention periods than either of the targeted interventions. Specifically, universal decolonization led to a 37% drop in the rate of MRSA infections (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.52 - 0.75), targeted decolonization led to a 25% decline (HR, 0.75; 95% CI, 0.63 - 0.89), and screening and isolation showed no significant change (HR, 0.92; 95% CI, 0.77 - 1.10). The difference between targeted decolonization and screening and isolation was not statistically significant (P = .09), but the difference was significant between universal decolonization and screening and isolation (P = .003).

Universal decolonization also resulted in significantly fewer ICU-attributed bloodstream infections from any pathogen, with a drop of 44% from baseline (HR, 0.56; 95% CI, 0.49 - 0.65) compared with screening and isolation (HR, 0.99; 95% CI, 0.84 - 1.16; P < .001). Targeted decolonization led to a smaller reduction that was significantly better than screening and isolation (HR, 0.78; 95% CI, 0.66 - 0.91).

The researchers saw no significant decline in MRSA bloodstream infections.

Universal decolonization prevented a single bloodstream infection for every 54 patients treated, the authors report, and 181 patients would have to be decolonized to detect 1 additional positive MRSA culture.

Michael B. Edmond, MD, MPH, professor of internal medicine, Virginia Commonwealth University Division of Infectious Diseases, and Richard P. Wenzel, MD, MSc, professor and chair, Virginia Commonwealth University Medical Center, Department of Internal Medicine, Richmond, write in an accompanying editorial that the results suggest that isolating patients with MRSA, which has long been the preferred strategy for reducing its spread and is required by law in 9 states, must stop.

"The implications of this study are highly important. The lack of effectiveness of active detection and isolation should prompt hospitals to discontinue the practice for control of endemic MRSA," the editorial authors write.

One potential downside of universal decontamination is the potential to develop resistant pathogens. Dr. Huang and colleges advise the initiation of surveillance programs to monitor for mupirocin and chlorhexidine resistance, but the editorialists say that because mupirocin resistance is well-documented, they "urge caution in implementing the universal use of mupirocin in patients in the ICU."

The study was funded by the Agency for Healthcare Research and the Centers for Disease Control and Prevention. One coauthor owns stock in Express Scripts. Sage Inc supplied free chlorhexidine-impregnated cloths to outside institutions for a research project led by one coauthor. One coauthor is on a medical advisory board for 3M and is a paid member of the Sage Inc speakers bureau. One coauthor conducts unpaid review of products under development by Sage Inc. Dr. Wenzel reports receiving funding from 3M, Sanofi-Pasteur, and Pfizer. The other authors and Dr. Edmond have disclosed no relevant financial relationships.

N Engl J Med. Published online May 29, 2013. Article full text, Editorial full text

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