Nasopharingeal bacterial and fungal colonization in HIV-positive versus HIV-negative adults

Objectives: To compare mucosal flora in HIV-positive and HIV-negative subjects, to assess chemosusceptibility patterns of carriage isolates and to evaluate possible predisposing factors within the two groups. Methods: We analyzed microbes isolated from nasopharyngeal swabs in virologically suppressed and immunologically stable HIV-positive adult outpatients (n=105) at baseline and after 12 months and in an age-matched cohort of HIV-negative outpatients (n=100) at baseline. Bacteria and Candida spp strains were isolated and identified through standard biochemical assays and chemosusceptibility tests were performed. Multi Locus Sequence Typing was also determined to characterize Staphylococcus aureus isolates from HIV-infected persistent carriers. Results: In HIV-positive patients a significantly higher rate of colonization by S. aureus as compared to HIV-negative controls was observed (19% vs 8%, p=0.02), with a relevant percentage of penicillin resistant strains (15% vs 0, p=0.24). Methicillin resistant strains were recovered only from HIV-positive subjects. Overall HIV-positive status was the only predictor of S. aureus colonization (OR 2.77, 95% CI 1.03;7.41, p=0.04). Conclusions: The nasopharyngeal bacterial flora differs between HIV-positive and HIV-negative subjects and appears relevant for possible development of staphylococcal infections in HIV-positive patients.