The utility of shotgun metagenomics to investigate the carriage of, and longitudinal changes in antimicrobial resistant Streptococcus pneumoniae, in the nasopharynx of South African infants.

Shotgun metagenomic sequencing of nasopharyngeal (NP) samples, from children enrolled in a PCV13-vaccinated South African birth cohort was used to explore strain-level pneumococcal colonization patterns and transmission dynamics, and associated antimicrobial-resistance determinants. NP swabs were collected at two-week intervals from birth through the first year of life from 137 infants. Pneumococcal isolates were serotyped and tested for phenotypic antimicrobial resistance. 196 NP samples from a subset of 23 infants were then selected based on changes in serotype or antimicrobial resistance. DNA was extracted directly from the enriched NP samples and shotgun metagenomic sequencing performed. Reads were assembled and aligned against reference pneumococcal genomes. in silico pneumococcal capsular, multilocus sequence typing, and resistome analyses were performed.