A randomized trial of MRSA-control strategies in the ICU

Posted by • June 12th, 2013

As healthcare workers we have become accustomed to seeing that yellow sign on the door indicating that a patient is on “Contact Precautions” to prevent the spread of healthcare-associated methicillin-resistant Staph aureus (MRSA) infection. So we dutifully wash our hands and put on gown and gloves prior to entering the room to examine the patient. In the ICU where I trained as a medical resident, all patients underwent nasal swab testing for the presence of MRSA. Patients who tested negative for MRSA could come off of precautions. Those who tested positive would stay on precautions for the duration of their hospital stay.

This week’s issue of NEJM presents the results of a three-armed randomized trial aimed at reducing MRSA colonization and bloodstream infections. MRSA control strategies are now standard at many ICUs across the United States, yet there is much debate as to how best to reduce hospital-acquired infections. The argument for targeted testing for MRSA is that this pathogen is particularly nasty: it is multi-drug resistant, highly virulent, and its prevalence in both the community and healthcare settings has been increasing with time. In 2011, NEJM published the results of a large Veteran’s Affairs MRSA screening initiative which was able to reduce health-care associated MRSA infections. Yet, an independent analysis of the data suggested that the reduction in infections may have been due to other factors besides the MRSA screening and isolation of those colonized. A separate randomized trial of MRSA screening and infection control measures that was also published in NEJM in 2011 found no reduction in MRSA infections as a result of the intervention. Furthermore, this study found that compliance with the infection control measures was poor: hand hygiene was used only 2/3 of the time and gowns were worn only ¾ of the time.

An unintended consequence of targeted screening for MRSA is that patients who test positive are not only isolated from other patients in the hospital – they become isolated from caregivers as well. A recent study from Maryland found that hospitalized patients on contact precautions received 36% fewer visits from healthcare workers and 24% fewer visits from family and friends as compared to their non-precaution peers. Given the questionable benefit of MRSA screening and isolation strategies for preventing healthcare-associated infections as well as the fact that such isolation can result in social isolation of patients, many in the infection control community have begun to explore other strategies for reducing the transmission of healthcare-associated infections.

Instead of simply placing MRSA-positive patients on contact precautions, another option exists: dropping the bacterial load with intra-nasal mupirocin and chlorhexidine bathing. The study published in this week’s NEJM compares standard MRSA screening and isolation with two other approaches to infection control. Arm 1 of the study underwent usual care with MRSA screening and contact precautions for those testing positive. Arm 2 also underwent screening for MRSA and standard contact precautions, but those testing positive underwent decolonization with mupirocin and chlorhexidine. Patients in the third arm of the study did not have MRSA screening, but instead they received universal decolonization with mupirocin and chlorhexidine. Because the patients in the third arm did not undergo MRSA screening, they were not placed on contact precautions unless they had a prior history of MRSA or their clinical cultures grew a pathogen requiring precautions.

This was a large study with more than 40 participating hospitals and over 70,000 patients. The results showed that those in the universal decolonization group had a greater reduction in MRSA-positive clinical cultures as well as a greater reduction in all-pathogen bloodstream infections as compared with targeted decolonization or standard screening and isolation strategies.  The study also examined rates of MRSA bloodstream infection and did not find any statistical difference between the groups.

In an accompanying editorial, Dr. Michael Edmond and Dr. Richard Wenzel write that the results of this study cast doubt on the benefits of MRSA screening and isolation strategies and “should prompt hospitals to discontinue [this] practice for control of endemic MRSA.” Furthermore, they note “A benefit will be a reduced proportion of patients in contact precautions, which is a patient unfriendly practice that interferes with care.”

While these data are compelling, the stakes are high – as many hospital-acquired infections are no longer reimbursed by some insurers. Further studies are needed to corroborate these findings as well as to examine whether a strategy of universal decolonization with mupirocin and chlorhexidine could lead to greater microbacterial resistance. A cost-benefit analysis would also be useful, given that MRSA screening and isolation programs can exact both a direct financial cost as well as the labor cost of nursing and support staff who must implement such programs. But more important than the potential for cost savings is the possibility that moving towards a strategy of universal decolonization could reduce the number of patients on contact precautions and remove an unfortunate barrier to visitation by health workers, family, and friends.

Connect with Dr. Colbert on Twitter: @jcolbertMD

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