April 01, 2015
2 min read

In HIV patients, specific behaviors linked to S. Aureus colonization, SSTI

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Specific behaviors, not HIV-related factors, increase the risk for Staphylococcus aureus colonization and subsequent skin and soft tissue infections, according to recent data.

“Studies have shown that the incidence of S. aureus infections is [six- to 18-fold] higher among HIV-infected, compared with HIV-uninfected, persons,” researchers wrote in Clinical Infectious Diseases. “Further, despite the availability of [highly active antiretroviral therapy (HAART)] in the developed world, HIV-infected persons continue to have elevated incidence rates of S. aureus infections, suggesting that factors beyond immunosuppression, such as specific behaviors, may be the most important risk factors.”

Researchers evaluated 322 adult HIV patients (median age, 42 years) without baseline S. aureus for incident colonization at five bodily locations: bilateral nostrils, pharynx, bilateral underarms, bilateral groin areas and perirectal region. The participants were evaluated every 6 months over a 2-year period. A control group of 293 participants without previous history of skin and soft tissue infections (SSTIs) also were examined for incident SSTIs over the course of the study period. 

Participants completed a questionnaire addressing various behaviors, including the use of antimicrobial soap, illicit drugs, alcohol or tobacco, and public gyms and showers, among others. The patients’ median HIV duration was 9.4 years, (IQR, 2.7-17.4) and 58% were enrolled in HAART. Thirty-two percent were colonized with S. aureus during the study period, with an incidence rate of 20.6 per 100 person-years (95% CI, 16.8-25.0).

Illicit drug use (HR = 4.26; 95% CI, 1.33-13.69) and use of public gyms (HR = 1.66; 95% CI, 1.04-2.66) were found to be predictors of colonization, while antimicrobial soap use was found to have a protective effect (HR = 0.50; 95% CI, 0.32-0.78). A separate multivariable model found that colonization in the perigenital area was linked to recent syphilis infection (HR = 4.63; 95% CI, 1.01-21.42). Incident SSTI occurred in 15% of participants, with an incidence rate of 9.4 cases per 100 person-years (95% CI, 6.8-12.7).

Incident S. aureus colonization (HR = 2.52; 95% CI, 1.35-4.69), use of public showers (HR = 2.59; 95% CI, 1.48-4.56) and hospitalization (HR = 3.54; 95% CI, 1.67-7.53) all were risk factors for incident SSTI. S. aureus colonization in the perigenital region was predictive of SSTIs, as well. HIV-associated factors such as CD4 cell count, HIV RNA levels and HAART use were not related to colonization or SSTIs.

According to the researchers, these findings suggest that while HIV-infected individuals remain at increased risk of S. aureus colonization, this is more associated with risky behaviors than with HIV-related factors.
“These data suggest that behavioral modifications may be the most important strategies in preventing S. Aureus colonization and SSTIs among HIV-infected persons,” they wrote. – by Jen Byrne

Disclosure: The researchers report no relevant financial disclosures.