Oropharyngeal colonization by Streptococcus pneumoniae among HIV-infected adults in Uganda: assessing prevalence and antimicrobial susceptibility.

Objectives: To evaluate characteristics of Streptococcus pneumoniae associated with oropharyngeal colonization in the Ugandan adult HIV population.

Methods: We conducted a cross-sectional study at the outpatient HIV clinic at the Joint Clinical Research Centre in Kampala, Uganda between July 2004 and February 2005. Six hundred HIV-infected individuals were interviewed and had oropharyngeal specimens collected. Pneumococci were isolated from these specimens and antimicrobial susceptibility patterns determined using standard microdilution methods. Serotypes of the pneumococcal isolates were evaluated by capsular swelling reaction with commercial antisera.

Results: The prevalence of oropharyngeal colonization with pneumococci was 18% (108/600). Thirty-two different pneumococcal serotypes were identified, and the most common were serotypes 3 (14.7%), 19F (6.4%), 23F (6.4%), and 16 (5.5%). Seventy-two percent of the isolates were penicillin (PCN) intermediate (MICs 0.12-1 microg/mL), the remainder all being PCN susceptible, and >99% were trimethoprim-sulfamethoxazole (TMP-SMX) resistant. Novel PCN intermediate serotypes included 7, 11, 16, 20, 22, 24, and 34. Only one isolate was resistant to macrolides, and resistance to other antibiotics was rare.

Conclusions: HIV-infected adults in Uganda are colonized with pneumococci that exhibit a high degree of TMP-SMX and PCN non-susceptibility, with several unique PCN non-susceptible serotypes that are not included in current vaccine preparations.