Invasive Serotype 35B Pneumococci Including an Expanding Serotype Switch Lineage, United States, 2015-2016

Emerg Infect Dis. 2017 Jun;23(6):922-930. doi: 10.3201/eid2306.170071.

Abstract

We used whole-genome sequencing to characterize 199 nonvaccine serotype 35B pneumococcal strains that caused invasive pneumococcal disease (IPD) in the United States during 2015-2016 and related these findings to previous serotype 35B IPD data obtained by Active Bacterial Core surveillance. Penicillin-nonsusceptible 35B IPD increased during post-pneumococcal 7-valent conjugate vaccine years (2001-2009) and increased further after implementation of pneumococcal 13-valent conjugate vaccine in 2010. This increase was caused primarily by the 35B/sequence type (ST) 558 lineage. 35B/ST558 and vaccine serotype 9V/ST156 lineages were implicated as cps35B donor and recipient, respectively, for a single capsular switch event that generated emergent 35B/ST156 progeny in 6 states during 2015-2016. Three additional capsular switch 35B variants were identified, 2 of which also involved 35B/ST558 as cps35B donor. Spread of 35B/ST156 is of concern in view of past global predominance of pathogenic ST156 vaccine serotype strains. Protection against serotype 35B should be considered in next-generation pneumococcal vaccines.

Keywords: United States; bacteria; invasive pneumococcal disease; penicillin-binding protein types; pneumococcal 13-valent conjugate vaccine; pneumococcal 7-valent conjugate vaccine; pneumococcal conjugate; pneumococci; recombination; respiratory infections; serotype 35B; serotype expansion; serotype switch; surveillance; switch lineage; vaccines.

MeSH terms

  • Gene Expression Regulation, Bacterial
  • Genome, Bacterial
  • Genotype*
  • Humans
  • Penicillin Resistance
  • Pneumococcal Infections / epidemiology*
  • Pneumococcal Infections / microbiology*
  • Serogroup*
  • Serotyping
  • Streptococcus pneumoniae / classification
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / genetics*
  • Streptococcus pneumoniae / immunology
  • United States