MRSA in the Groin of HIV Patients Ups Infection Risk

Steven Fox

March 13, 2013

Colonization of methicillin-resistant Staphylococcus aureus (MRSA) in the groin area of HIV-infected adults increases risk for subsequent clinical infection, according to results of a prospective study carried out by the Centers for Disease Control and Prevention.

Phillip J. Peters, MD, Medical Officer, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, and colleagues published their results online March 13 and in the April issue of Emerging Infectious Diseases.

"Data on the interaction between [MRSA] colonization and clinical infection are limited," the authors write. They say that colonization with S aureus is a risk factor for subsequent clinical infection and that the site of colonization may also play a role in subsequent risk.

For example, they note that although the anterior nares is usually thought of as the primary reservoir of MRSA, some variants of the bacteria may more often colonize the buttocks, genitals, and perineum.

"Improving our understanding of the interaction between MRSA colonization and clinical infection among persons with HIV is necessary so that effective prevention strategies can be developed for this population," they write.

Therefore, the researchers conducted a prospective cohort study of 600 HIV-infected adults (98% men) recruited from the Veterans Affairs (VA) Medical Center in Atlanta, Georgia. All patients enrolled in the study received outpatient care at the center's HIV clinic from September 2007 through April 2008.

The researchers took swabs of the nares and groin and cultured them for S aureus. The cultures were performed at enrollment and again at 6 months and 12 months.

The cultures showed evidence of MRSA colonization in 13% to 15% of the participants at baseline, 6 months, and 12 months. Of those participants colonized with MRSA, 41% had colonization in the nares only, 21% had colonization in the groin only, and 38% exhibited colonization in both sites.

During a median follow-up of 2.1 years, 25 patients in the cohort developed 29 MRSA clinical infections.

In a multivariate analysis, the authors found that MRSA clinical infection was significantly associated with MRSA colonization of the groin (adjusted risk ratio, 4.8) and a history of MRSA infection (adjusted risk ratio, 3.1). The analysis adjusted for a variety of factors, including CD4 cell count, history of an abscess, renal insufficiency, a history of syphilis, use of certain antistaphylococcal drugs in the previous year, contact with a prison or jail, and certain hygienic factors.

"Given the frequency of MRSA colonization in the groin and its association with clinical infection, MRSA prevention strategies (both hygienic practices and decolonization treatments) with HIV-infected adults should be used to prevent or eliminate colonization at this anatomic site to reduce MRSA clinical infections in this population," they conclude.

This research was supported by the Division of HIV/AIDS Prevention and the Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia. The authors have disclosed no relevant financial relationships.

Emerg Infect Dis. Published online March 13, 2013. Full text