Methods: From March 2014-May 2015, we enrolled 138 HIV-1-infected (HIV+) and 93 uninfected controls aged 18-55 years without other underlying immunosuppression, lung disease, or antibiotic use within 3 months of enrollment. NP and OP samples were collected using flocked swabs in Amies media. NP samples were inoculated onto sheep’s blood agar ± gentamicin, incubated, and examined for alpha-hemolytic colonies susceptible to optochin and soluble in bile acids, findings diagnostic of Spn. In parallel, we tested DNA extracted directly from the NP samples by quantitative PCR for total bacterial 16S rDNA and the Spn-specific lytA gene, detection of which under 40 cycles met molecular criteria for Spn.
Results: Among HIV+ subjects (mean 586 CD4+ T cells/µL, plasma HIV RNA 15,816 copies/mL), 78% were on ART and 79% had received pneumococcal vaccination. Overall, bacterial DNA was detectable in all samples. However, only 4% of HIV+ subjects and 3% of controls were colonized with Spn (not significant, p = 0.74). 5 subjects were positive by culture and lytAPCR, 4 by PCR alone. The majority of colonized individuals were sampled during local influenza season. 3 of 6 colonized HIV-1-infected subjects had received 23-valent pneumococcal vaccine within 1-7 years pre-enrollment.
Conclusion: Using rigorous culture dependent and independent methods, the frequency of colonization with Spn among adults (3-4%) was lower than previously reported in both HIV+ and control adults in the U.S. (9-14%). These findings may be attributable to infrequent exposure to young children, high rates of pneumococcal vaccination in HIV+ subjects, and widespread vaccination of children in the community. Future directions include analysis of OP samples for Spn by PCR, characterization of NP and OP microbiomes in the two groups, and monitoring the incidence of pneumococcal disease among HIV+ subjects in the community.
T. Wright, None
E. M. Gardner, None
E. N. Janoff, Merck vaccines: Consultant , Consulting fee
Pfizer: Research Contractor , Research support
D. Frank, None