High Streptococcus pneumoniae colonization prevalence among HIV-infected Kenyan parents in the year before pneumococcal conjugate vaccine introduction

Background: Streptococcus pneumoniae is a leading cause of pneumonia, meningitis and sepsis in developing countries, particularly among children and HIV-infected persons. Pneumococcal oropharyngeal (OP) or nasopharyngeal (NP) colonization is a precursor to development of invasive disease. New conjugate vaccines hold promise for reducing colonization and disease. Methods: Prior to introduction of 10-valent pneumococcal conjugate vaccine (PCV10), we conducted a cross-sectional survey among HIV-infected parents of children <5years old in rural Kenya. Other parents living with an HIV-infected adult were also enrolled. After broth enrichment, NP and OP swabs were cultured for pneumococcus. Serotypes were identified by Quellung. Antimicrobial susceptibility was performed using broth microdilution. Results: We enrolled 973 parents; 549 (56.4%) were HIV-infected, 153 (15.7%) were HIV-uninfected and 271 (27.9%) had unknown HIV status. Among HIV-infected parents, the median age was 32years (range 15-74) and 374/549 (68%) were mothers. Pneumococci were isolated from 237/549 (43.2%) HIV-infected parents and 41/153 (26.8%) HIV-non-infected parents (p=0.0003). Colonization with PCV10 serotypes was not significantly more frequent in HIV-infected (12.9%) than HIV-uninfected parents (11.8%; p=0.70). Among HIV-infected parents, cooking site separate from sleeping area and CD4 count >250 were protective (OR=0.6; 95% CI 0.4, 0.9 and OR=0.5; 95% CI 0.2, 0.9, respectively); other associations were not identified. Among 309 isolates tested from all parents, 255 (80.4%) were penicillin non-susceptible (MIC ≥0.12g/ml). Conclusions: Prevalence of pneumococcal colonization is high among HIV-infected parents in rural Kenya. If young children are the pneumococcal reservoir for this population, PCV10 introduction may reduce vaccine-type colonization and disease among HIV-infected parents through indirect protection.