HIV patients have six-fold higher rates of CA-MRSA

Epidemic intersecting with community staph strains

The HIV epidemic has converged with emerging community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), a complication that raises both new challenges and opens possible avenues to prevention, researchers report.1

They found that the risk of CA-MRSA skin and soft tissue infections (SSTIs) in Cook County Health and Hospitals System (CCHHS) in Chicago was more than six-fold higher for HIV-infected patients than it was for HIV-negative patients. CA-MRSA caused increasing numbers of SSTIs among HIV-infected patients in both community and hospital settings.

Using electronic data, the authors retrospectively studied HIV-infected patients with community-associated S. aureus SSTIs who received medical care during the period 2000-2007 at the multicenter, regional CCHHS. From period 1 (2000-2003) to period 2 (2004-2007), there was a nearly four-fold increase in CA-MRSA SSTIs among HIV-infected patients. Among hospitalized HIV-infected patients, the incidence of CA-MRSA SSTIs increased more than four-fold from period 1 to period 2. This increase in CA-MRSA disease was in addition to -- not in replacement of - skin and tissue infections with susceptible staph strains in the community.

HIV infection is an apparent risk factor for CA-MRSA infection. However, variables in addition to HIV-related immunosuppression — such as housing type and location of residence — may contribute to the risk of MRSA acquisition. Prior research has found that MRSA colonization is found among HIV-infected patients without significant immune dysfunction, suggesting that factors other than CD4+ count may contribute to increased colonization burden, the authors note. In addition, the CA-MRSA infection epidemic has impacted certain populations with high-risk behaviors or who have alternative housing (e.g., men who have sex with men, illicit drug users, and prisoners). The researchers found that "high-risk" zip codes in Cook County -- those with high numbers of residents who were previously incarcerated — were associated with increased risk of CA-MRSA acquisition among HIV-infected patients.

"The initial focus of CA-MRSA infection in high-risk zip codes suggests that an early epidemic-driver was transmission of strains among networks of high-risk individuals," they concluded. "Our findings and the findings of others suggest that particular populations are disproportionately affected by the CA-MRSA infection epidemic. ... Particular community settings that appear to be epicenters for the spread of CA-MRSA (e.g., prisons and high-risk zip codes) may represent targets for prevention efforts."

Reference

  1. Popovich KJ, Weinstein RA, Aroutcheva A, et al. Community-Associated Methicillin-Resistant Staphylococcus aureus and HIV: Intersecting Epidemics Clinical Infectious Diseases 2010;50:979-987.