Certain patient populations more likely to carry MRSA

Hospitals performing active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) should focus on three types of patients more likely to carry the germ in their nasal passages, a new study recommends.

Led by Leonard Mermel, medical director of the department of epidemiology and infection control at Rhode Island Hospital, the study of 2,055 patients found that MRSA was present in the noses of 20 percent of long-term elder care patients, 16 percent of HIV-infected patients, and 14 percent and 15 percent of inpatient and outpatient kidney dialysis patients.

Although the presence of MRSA does not indicate infection, it heightens an individual's risk of developing MRSA-related pneumonia, bloodstream infection and surgical site infection, the research concludes. About 1 percent of all people in the general population carry MRSA in their nose, and the rate jumps to 4 percent among healthcare workers.

Hospital-related MRSA strains were most commonly detected in the patients studied, except for with HIV-positive patients, who mostly carried a more virulent community-associated strain. Researchers also reported vast differences in the number of MRSA colonies in the noses of the patients in the study, noting that heavy MRSA colonization of the nose is an independent risk factor for the development of a surgical site infection.

The study appears online and in the June print issue of the journal Infection Control and Hospital Epidemiology.

Meanwhile, at yesterday's American Society for Biochemistry and Molecular Biology's annual meeting, Harvard researcher Roy Kishony gave a presentation titled "Driving backwards the evolution of antibiotic resistance." The research takes a new look at how best to select drug combinations to fight resistant bacteria. While the traditional approach has been to select antibiotics with the highest individual kill rates, Kishony explains, interactions may occur that render the multi-drug regimen weaker than one antibiotic would be alone.

The Kishony lab is using this discovery to set up a drug screening system that could identify novel drug combinations that could hinder the development of resistance but still act highly effectively. "Our approach is going to ask how these drugs affect the competition between resistant versus sensitive bacterial strains," Kishony says.

To learn more:
- read this Rhode Island Hospital news brief
- read this HealthDay News article
- check out this Infection Control and Hospital Epidemiology abstract
- read this article in The Medical News

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