Description of macrolide-resistant and potential virulent clones of Streptococcus pyogenes causing asymptomatic colonization during 2000-2006 in the Lisbon area

Eur J Clin Microbiol Infect Dis. 2012 May;31(5):849-57. doi: 10.1007/s10096-011-1384-x. Epub 2011 Oct 21.

Abstract

The asymptomatic oropharyngeal colonization rate by Streptococcus pyogenes was 10.7% in children (901 among 8,405 children 0-16 years old) and 3.3% in adults (37 among 1,126 households of children) in the Lisbon area during 2000-2006. Macrolide-resistant S. pyogenes from children (n = 149) was variable with time: 9.8-10.7% in 2000-2002, 28.1% in 2003, 19.6-2.7% in 2004-2005 and 14.6% in 2006. Eight lineages (97.3% of isolates) were identified based on at least 80% similarity of PFGE patterns, T types, emm types and multilocus sequence types (ST). The elevated frequency of macrolide resistance was associated with M phenotype lineages I (emm12/ST36) and V (emm4, emm75/ST39 and a novel emmstMrp6 type) and with one cMLS(B) lineage IV (emm28/ST52) known to be associated with upper respiratory tract and invasive infections. Significant associations (p < 0.05) between emm type/virulence genotype were found, such as emm1/speA (+) ssa (-), emm4/ssa (+) prtF1 (+), emm12/speA (-) ssa (-). The high prevalence (>20%) of speC, prtF1 or ssa was probably caused either by clonal dissemination (speC), or to horizontal gene transfer events (prtF1 and ssa). This report contributes to a better understanding of the molecular epidemiology and evolution of macrolide-resistant S. pyogenes causing symptom-free oropharyngeal colonization. These colonizing strains carry macrolide resistance and virulence genes capable of being transferred to other bacterial species sharing the same niche.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Anti-Bacterial Agents / pharmacology*
  • Antigens, Bacterial / genetics
  • Bacterial Outer Membrane Proteins / genetics
  • Carrier Proteins / genetics
  • Carrier State / epidemiology*
  • Carrier State / microbiology
  • Child
  • Child, Preschool
  • Cluster Analysis
  • Drug Resistance, Bacterial*
  • Electrophoresis, Gel, Pulsed-Field
  • Genotype
  • Humans
  • Infant
  • Macrolides / pharmacology*
  • Molecular Epidemiology
  • Multilocus Sequence Typing
  • Oropharynx / microbiology
  • Portugal / epidemiology
  • Prevalence
  • Streptococcal Infections / epidemiology*
  • Streptococcal Infections / microbiology
  • Streptococcus pyogenes / classification
  • Streptococcus pyogenes / drug effects
  • Streptococcus pyogenes / isolation & purification*
  • Streptococcus pyogenes / pathogenicity
  • Virulence
  • Virulence Factors / genetics

Substances

  • Anti-Bacterial Agents
  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Carrier Proteins
  • Macrolides
  • Virulence Factors
  • streptococcal M protein