Increased penicillin nonsusceptibility of nonvaccine-serotype invasive pneumococci other than serotypes 19A and 6A in post-7-valent conjugate vaccine era

J Infect Dis. 2010 Mar;201(5):770-5. doi: 10.1086/650496.


According to population-based invasive pneumococcal surveillance in the United States during 2007, 898 (26%) of 3,511 isolates were penicillin nonsusceptible. Non-7-valent pneumococcal conjugate vaccine (PCV7) serotypes other than 19A accounted for 40% of these penicillin-nonsusceptible isolates; of these, serotypes 15A (11%), 23A (8%), 35B (8%), and 6C (5%) were most common (cumulatively 32% of penicillin-nonsusceptible isolates). Each except 6C represented a single serotype and clonal complex combination that predated the introduction of PCV7. We evaluated the genetic characteristics and nonsusceptibility to penicillin of non- PCV7 serotypes, and we found increased proportions of specific penicillin-nonsusceptible clones in serotypes 15A, 23A, 35B, and 6C, which potentially indicates a basic change of population structure within these individual serotypes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Typing Techniques
  • Child
  • Child, Preschool
  • Cluster Analysis
  • DNA Fingerprinting
  • Female
  • Genotype
  • Heptavalent Pneumococcal Conjugate Vaccine
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Penicillin Resistance*
  • Penicillins / pharmacology*
  • Pneumococcal Infections / microbiology*
  • Pneumococcal Vaccines / immunology*
  • Prevalence
  • Sequence Analysis, DNA
  • Serotyping
  • Streptococcus pneumoniae / classification*
  • Streptococcus pneumoniae / drug effects*
  • Streptococcus pneumoniae / isolation & purification
  • United States / epidemiology


  • Anti-Bacterial Agents
  • Heptavalent Pneumococcal Conjugate Vaccine
  • Penicillins
  • Pneumococcal Vaccines