Analysis of multidrug resistance in the predominant Streptococcus pneumoniae serotypes in Canada: the SAVE study, 2011-15

J Antimicrob Chemother. 2018 Jul 1;73(suppl_7):vii12-vii19. doi: 10.1093/jac/dky158.

Abstract

Objectives: This study assessed MDR invasive isolates of Streptococcus pneumoniae, in relation to serotype evolution in Canada between 2011 and 2015 as part of the annual SAVE study.

Methods: As part of a collaboration between the Canadian Antimicrobial Resistance Alliance and Public Health Agency of Canada-National Microbiology Laboratory, 6207 invasive isolates of S. pneumoniae were evaluated. All isolates were serotyped and had antimicrobial susceptibility testing performed, in accordance with CLSI guidelines (M07-A10, 2015). Complete susceptibility profiles were available for 6001 isolates. MDR was defined as resistance to three or more classes of antimicrobial agents (with penicillin MIC ≥2 mg/L defined as resistant).

Results: The overall rate of MDR S. pneumoniae was 6.2% (372/6001) in SAVE, decreasing significantly from 8.5% in 2011 to 5.6% in 2015 (P = 0.0041). MDR was observed in 32 serotypes, with serotypes 15A and 19A predominating (26.6% and 41.7% of the MDR isolates, respectively). The overall proportion of serotypes 19A, 7F and 33A decreased significantly (P < 0.0001) throughout the study. The annual proportion of serotypes 7C, 8, 9N, 10A, 20, 24F, 29, 31, 33F, 35B and 38 increased throughout the study; however, among these increasing serotypes, MDR was only notable (>5%) for 24F and 33F.

Conclusions: In 2015, 56.3% of invasive MDR S. pneumoniae were serotypes included in the PCV-13 vaccine. PCV-13 includes the most commonly identified serotype, 19A; however, other increasingly important MDR serotypes, such as 15A, 24F and 33F, are notably not in the currently used vaccines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology*
  • Canada
  • Child
  • Child, Preschool
  • Clarithromycin / pharmacology
  • Drug Resistance, Multiple, Bacterial*
  • Humans
  • Infant
  • Infant, Newborn
  • Microbial Sensitivity Tests
  • Middle Aged
  • Penicillins / pharmacology
  • Pneumococcal Infections / blood
  • Pneumococcal Infections / microbiology
  • Pneumococcal Vaccines / administration & dosage
  • Serogroup
  • Serotyping
  • Streptococcus pneumoniae / classification
  • Streptococcus pneumoniae / drug effects*
  • Vancomycin / pharmacology
  • Young Adult

Substances

  • Anti-Bacterial Agents
  • Penicillins
  • Pneumococcal Vaccines
  • Vancomycin
  • Clarithromycin