Nasopharyngeal carriage and serotype distribution of Streptococcus pneumoniae among HIV-infected children aged >6 years: before and after vaccination of 13-valent pneumococcal conjugate vaccine.

Purpose: The objective of this study was to determine the prevalence of colonization, serotype distribution, and antimicrobial susceptibility profile of Streptococcus pneumoniae (Pneumococcus) isolated from human immunodeficiency virus (HIV)-infected children before and after single-dose of 13-valent pneumococcal conjugate vaccine (PCV13) vaccination.

Materials and methods: We conducted a prospective cohort study among HIV-infected children above six years of age in Jakarta, Indonesia. Nasopharyngeal swabs were collected from 50 children before vaccination, 12 months, and 18 months after PCV13 vaccination. The swabs were evaluated by bacterial culture, and serotyping were performed using sequential multiplex polymerase chain reactions and Quellung reactions. Antimicrobial susceptibility profiles were determined using the disk diffusion method.

Results: We found Streptococcus pneumoniae colonized 46% (23/50) of total children enrolled before vaccination, which decreased to 19% (n=9/47) at 12 months post-vaccination and 29% (14/48) at 18 months post-vaccination. There was no significant difference in the prevalence of pneumococcal colonization between vaccinated and unvaccinated HIV-infected children (p>0.05). There was a significant decrease in pneumococcal colonization between the baseline, 12 months, and 18 months after vaccination among vaccinated children (p<0.05). Vaccine-type (VT) serotypes (6B, 23F, and 19A) were more prevalent than non-vaccine serotypes before vaccination. Non-vaccine type (NVT) serotypes (6C, 15C) were more prevalent at 12 months post-vaccination. VT serotypes were found at 18 months post-vaccination in vaccinated children. There was a high prevalence of antimicrobial resistance to S. pneumoniae isolates to oxacillin, tetracycline, and sulfamethoxazole-trimethoprim before and after vaccination.

Conclusion: There was a decrease in pneumococcal carriage after PCV vaccination in HIV-infected children, accompanied by changes in serotype distribution from VT serotypes to NVT serotypes.