Seven-year surveillance of emm types of pediatric Group A streptococcal pharyngitis isolates in Western Greece

PLoS One. 2013 Aug 19;8(8):e71558. doi: 10.1371/journal.pone.0071558. eCollection 2013.

Abstract

Background: An experimental 26-valent M protein Group A streptococcal (GAS) vaccine has entered clinical studies. Pharyngeal GAS emm type surveillances in different areas and time-periods enhance the understanding of the epidemiology of GAS pharyngitis. Moreover, these surveillances, combined with the data on GAS invasive disease, can play a significant role in the formulation of multivalent type-specific vaccines.

Methods: During a 7-year period (1999-2005), 2408 GAS isolates were recovered from consecutive children with pharyngitis in Western Greece. The overall macrolide resistance rate was 22.8%. Along the study period we noted a tendency towards significantly decreased rates of resistance, with the lowest rates occurring in 2002 (15.3%), 2003 (15%) and 2004 (16.7%). A random sample of isolates from each year, 338 (61.7%) of the 548 macrolide-resistant and 205 (11%) of the macrolide-susceptible, underwent molecular analysis, including emm typing.

Results: The 543 typed isolates had 28 different emm types. A statistically significant association was found between macrolide resistance and emm4, emm22 and emm77, whereas emm1, emm3, emm6, emm12, emm87 and emm89 were associated with macrolide susceptibility. A significant yearly fluctuation was observed in emm4, emm28 and emm77. The most common macrolide-resistant GAS were emm77 isolates harboring erm(A), either alone or in combination with mef(A), emm4 carrying mef(A), emm28 possessing erm(B), emm75 carrying mef(A), emm12 harboring mef(A) and emm22 carrying erm(A). We estimated that 82.8% of the isolates belonged to emm types included in the novel 26-valent M protein vaccine. The vaccine coverage rate was determined mainly by the increased frequency of nonvaccine emm4 isolates.

Conclusions: A limited number of emm types dominated among macrolide-susceptible and macrolide-resistant GAS isolates. We observed seasonal fluctuations, which were significant for emm4, emm28 and emm77. This type of data can serve as baseline information if the novel 26-valent M protein GAS vaccine is introduced into practice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Antigens, Bacterial / immunology
  • Bacterial Outer Membrane Proteins / immunology
  • Carrier Proteins / immunology
  • Child
  • Child, Preschool
  • Drug Resistance, Bacterial / drug effects
  • Genes, Bacterial / genetics*
  • Genotype
  • Greece / epidemiology
  • Humans
  • Infant
  • Infant, Newborn
  • Macrolides / pharmacology
  • Microbial Sensitivity Tests
  • Pharyngitis / epidemiology*
  • Pharyngitis / immunology
  • Pharyngitis / microbiology*
  • Pharyngitis / prevention & control
  • Pharynx / drug effects
  • Pharynx / microbiology
  • Pharynx / pathology
  • Phenotype
  • Population Surveillance*
  • Streptococcal Vaccines / immunology
  • Streptococcus pyogenes / classification
  • Streptococcus pyogenes / drug effects
  • Streptococcus pyogenes / genetics*
  • Streptococcus pyogenes / isolation & purification*

Substances

  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Carrier Proteins
  • Macrolides
  • Streptococcal Vaccines
  • streptococcal M protein

Grants and funding

This study was supported by a grant from the German Ministry of Health (Bundesministerium für Gesundheit) and the 3089 grant from the Research Committee of the University of Thessaly. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.