Antimicrobial resistance in relation to sero- and genotypes among invasive Streptococcus pneumoniae in Finland, 2007-2011

Microb Drug Resist. 2014 Apr;20(2):124-30. doi: 10.1089/mdr.2013.0156. Epub 2013 Nov 22.

Abstract

Aim: We studied the serotypes and antimicrobial resistance of the invasive Streptococcus pneumoniae that had been isolated in Finland during 5 years. The 10-valent vaccine was introduced into the National Vaccination Programme in September 2010.

Methods: We examined the antimicrobial resistance and serotype distribution of the invasive pneumococci (n=4,194) that had been isolated in Finland during 2007-2011. The penicillin-resistant (PEN R) (≥4 mg/L) isolates (n=12) were genotyped by MLST.

Results: Serotype 14 was consistently the most prominent serotype, covering 18.0-20.1% of all the isolates. The proportion of serotypes 3, 19A, and 22F increased significantly, while that of 6B and the PCV10 vaccine serotypes combined decreased. PEN nonsusceptibility (≥0.12 mg/L) increased, ranging from 14.4% to 23.2% by year, and was the highest (28.5%) among the 0-2 year olds. The PEN and/or erythromycin (ERY) nonsusceptibility of several vaccine serotypes (4, 6B, 14, and 19F) increased significantly over the study period. The ERY nonsusceptibility was 26.6%. There was limited diversity among the PEN R isolates; all were a part of serotype 19F, 19A, or 14, and two globally disseminated genetic lineages carrying one or both pilus-encoding islets.

Conclusions: High and/or increasing nonsusceptibility rates underline the importance of monitoring the serotype distribution and antimicrobial susceptibility of pneumococci, especially after large-scale vaccination.

MeSH terms

  • Adolescent
  • Adult
  • Anti-Bacterial Agents / therapeutic use
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Erythromycin / therapeutic use
  • Fimbriae, Bacterial / genetics*
  • Finland / epidemiology
  • Genotype*
  • Humans
  • Infant
  • Infant, Newborn
  • Microbial Sensitivity Tests
  • Middle Aged
  • Multilocus Sequence Typing
  • Penicillins / therapeutic use
  • Pneumococcal Infections / epidemiology*
  • Pneumococcal Infections / immunology
  • Pneumococcal Infections / microbiology
  • Pneumococcal Infections / prevention & control
  • Pneumococcal Vaccines / administration & dosage
  • Pneumococcal Vaccines / immunology
  • Serotyping
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / genetics*
  • Streptococcus pneumoniae / isolation & purification
  • Vaccination

Substances

  • Anti-Bacterial Agents
  • Penicillins
  • Pneumococcal Vaccines
  • Erythromycin