December 19, 2017
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State-mandated MRSA surveillance fails to reduce prevalence in ICUs

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A state law that requires health care providers to actively monitor patients in the ICU for MRSA colonization failed to meet its objective to reduce MRSA prevalence, highlighting the limits of such legislation, according to researchers.

“Our citywide observational findings, together with results from recent clinical trials, suggest that it is time for states to reconsider the practice of legislating MRSA active surveillance,” Michael Y. Lin, MD, MPH, assistant professor of medicine at Rush University Medical Center, and colleagues wrote in Clinical Infectious Diseases.

In 2007, Illinois became the first of several states to mandate the MRSA “search and isolate” strategy, which uses active surveillance to identify MRSA-colonized ICU patients and place them in contact precautions, according to the researchers.

“The ‘search and isolate’ strategy has been used to control MRSA during outbreaks, but its role in controlling MRSA in the non-outbreak (endemic) setting, which is the current status of most hospitals in the United States, is controversial,” they wrote.

For their study, Lin and colleagues evaluated whether the “search and isolate” strategy reduced the prevalence of MRSA colonization 5 years after implementation. Their analysis included data from 25 hospitals in Chicago that were surveyed from 2008 to 2013.

Among 3,909 adult ICU patients, 11.1% were colonized with MRSA. Overall, most patients (93%) were tested for MRSA in compliance with state law. Over the study period, the number of hospitals reporting routine daily chlorhexidine gluconate bathing in at least one ICU increased from 5 to 17, and the proportion of patients screened by PCR increased from 42% to 50%.

Despite these findings, the prevalence of MRSA colonization remained unchanged (RR = 0.97; 95% CI, 0.89-1.05). In addition, approximately four in 10 patients colonized with MRSA were not in contact precautions at the time of the survey. Of these patients, 8% were never screened upon admission, 9% were in a lag period between a positive screening result and initiation of contact precautions, 15% were waiting for culture results that eventually tested positive and 69% had a negative result upon admission, which either suggests that MRSA screening lacked sensitivity or the patients acquired MRSA in the ICU.

“Hospitals could improve routine MRSA testing sensitivity (eg, testing more body sites or performing serial testing) to incrementally increase the proportion of MRSA-colonized patients on contact precautions,” Lin and colleagues noted. “However, it is unclear whether higher levels of contact precautions would lead to decreased transmission and infection for endemic MRSA.”

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According to the researchers, the only randomized control trial assessing the efficacy of active MRSA surveillance also showed that the strategy failed to significantly reduce colonization and infection. In contrast, more recent data from the REDUCE-MRSA trial demonstrated that universal decolonization among all patients in the ICU with nasal mupirocin and chlorhexidine gluconate bathing was superior to active MRSA surveillance and contact precautions in reducing MRSA prevalence.

“Mathematical modeling suggests that a MRSA ‘search and isolate’ strategy has a negligible effect on colonization prevalence, simply because the majority of patients colonized with MRSA in the ICU are already colonized at the time of admission, and endemic ICU transmission rates of MRSA are low in acute care hospitals,” Lin and colleagues wrote. “Importantly, we note that the legislation in Illinois, as currently written, does not allow hospitals to stop active surveillance while adopting the more effective universal decolonization approach as tested in REDUCE-MRSA, highlighting a major drawback to legislating specific hospital infection control practices.” – by Stephanie Viguers

Disclosures: Lin reports receiving research support from OpGen and Sage Products, as well as an investigator-initiated grant from CareFusion Foundation. Please see the study for all other authors’ relevant financial disclosures.

MRSA infographic