To Prevent MRSA In Hospitals, Don't Prevent Only MRSA

Practically since the multi-drug resistant bacterium MRSA became a public health issue in the 1960s, health care has been arguing over how best to prevent its spread — particularly in hospitals, where the bug first became a problem and where the most vulnerable patients are concentrated. The camps break down, more or less, into procedures which look for MRSA specifically, and procedures which reduce the risk of spreading any pathogen in the hospital environment. The MRSA-specific strategies, popular in Europe and in some health-care systems in the US, involve checking patients to see who is carrying the bacterium, and then taking extra care with those who are positive, usually by isolating them within the hospital and making sure health care workers wear protective gear when they encounter them. The more general ones involve mandating actions, usually but not always things  that health care workers do — such as washing their hands more regularly and bathing patients with disinfectant — which will reduce the risk of not only MRSA transmission but of any other pathogen as well.

The back and forth between these views has been intense and prolonged; most of the infectious-disease meetings I’ve attended over the past 6 years have staged some sort of debate between representatives of the two sides. In the United States, the “active detection and isolation” strategy (often just called “search and destroy”) has been ascendant; among other things, it has been written into law in at least nine states, and adopted by the VA healthcare system. It has been demonstrated to work (though that demonstration was later challenged), but it is costly in staff time and also in equipment, since detection is usually done by molecular methods; and isolation has been shown to be rough on patients as well.

In the latest round — though given the contentiousness of this debate, probably not the last — a strong study just published in the New England Journal of Medicine, describing a careful trial of both systems, establishes that the non-specific strategy works better to reduce not just MRSA, but hospital-associated infections of all kinds.

The NEJM study was conducted at 43 hospitals, all within the nationwide system Hospital Corporation of America,  and took in 74 intensive-care units and more than 74,000 patients over 18 months (preceded by 12 months of observation and 3 months of phase-in). Any patients admitted to an ICU got one of three interventions:

  1. Active detection and isolation: swabbing patients before ICU admission and putting any of them who were carrying the bacterium or had a previous infection under “contact precautions”: being housed by themselves or in a room with another MRSA patient, and requiring gowns and gloves for anyone who enters. (This was HCA’s standard of care in its ICUs.)
  2. Targeted decolonization: MRSA testing followed, for any patient carrying the bacterium, by contact precautions, plus mupirocin gel placed into the nostrils twice a day, plus daily bathing/wiping with the disinfectant chlorhexidine (Hibiclens is a common brand name).
  3. Universal decolonization: No testing; but contact precautions, twice-daily mupirocin and daily chlorhexidine for every ICU patient.

And the results were: Universal decolonization was the most effective, reducing MRSA-positive cultures by 37 percent and bloodstream infections from any pathogen, not just MRSA, by 44 percent. In second place: targeted decolonization. In last place: active detection and isolation, which made almost no difference to the occurrence of bloodstream infections from MRSA or any other pathogen, or to MRSA carriage by patients. The authors (from eight hospitals or systems, plus the Centers for Disease Control and Prevention) say:

Several factors may account for our observation that universal decolonization had a greater preventive effect than the two other strategies. First, chlorhexidine reduces skin colonization by many pathogens, thus protecting patients in the ICU from their own microbiota during a period of heightened vulnerability to infection. Second, universal decolonization reduces the environmental microbial burden, reducing opportunities for patient-to-patient transmission. Third, universal decolonization began on the first ICU day, thus avoiding the delay in decolonization pending the results of screening tests.

In a companion editorial, Michael Edmond and Richard Wenzel of Virginia Commonwealth University School of Medicine add context and ask what comes next:

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. A benefit will be a reduced proportion of patients requiring contact precautions, which is a patient-unfriendly practice that interferes with care.10 In addition, the folly of pursuing legislative mandates when evidence is lacking has been shown, and laws mandating MRSA screening should be repealed.

Wenzel and Edmond (who blogs at Controversies in Hospital Infection Prevention along with Dan Diekema and  friend-of-Superbug Eli Perencevich) title their editorial “Case Closed.” Given the long controversy over MRSA-prevention methods, it will be interesting to see if that is the case.




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