Capsule switching and antimicrobial resistance acquired during a repeated Streptococcus pneumoniae pneumonia episodes

Seven repeated pneumonia episodes caused by a Streptococcus pneumoniae strain were analyzed in a pediatric patient with cerebral palsy. A total of 10 S. pneumoniae strains were obtained and serotype 6B was isolated from the first 5 episodes whereas 6A was isolated from the last 2. Whole genome sequencing showed clonality of the 10 isolates with 10 SNVs in the genomes. Among these SNVs, one single point mutation in the wciP gene was presumed to relate to the serotype switching from 6B to 6A, and the others in parC and gyrA were related to fluoroquinolone resistance.