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Description of macrolide-resistant and potential virulent clones of Streptococcus pyogenes causing asymptomatic

R Pires1, D Rolo, A Morais

  • 1Centro de Recursos Microbiológicos, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus de Caparica, 2829-516, Caparica, Portugal.

European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology
|October 21, 2011
PubMed

Insights

Streptococcus pyogenes colonization is common in children. Macrolide-resistant strains, often carrying virulence genes, are linked to specific lineages and may transfer resistance genes, impacting public health.

Area of Science:

  • Microbiology
  • Epidemiology
  • Molecular Biology

Background:

  • Asymptomatic oropharyngeal colonization by Streptococcus pyogenes is a significant public health concern.
  • Understanding the epidemiology and resistance patterns of S. pyogenes is crucial for effective treatment and prevention strategies.

Purpose of the Study:

  • To investigate the prevalence and molecular characteristics of asymptomatic Streptococcus pyogenes colonization in Lisbon.
  • To analyze the temporal trends and genetic factors associated with macrolide resistance in colonizing S. pyogenes strains.
  • To identify virulence genotypes and their association with specific emm types and lineages.

Main Methods:

  • Population-based study in the Lisbon area from 2000-2006.
  • Molecular typing of S. pyogenes isolates using Pulse Field Gel Electrophoresis (PFGE), T typing, emm typing, and multilocus sequence typing (MLST).
  • Analysis of macrolide resistance phenotypes and associated virulence genes (speA, ssa, prtF1, speC).

Main Results:

  • The colonization rate was 10.7% in children and 3.3% in adults.
  • Macrolide resistance in pediatric isolates varied over time, with a peak in 2003.
  • Eight major lineages accounted for 97.3% of isolates, with specific lineages (I, IV, V) strongly associated with macrolide resistance.
  • Significant associations were found between emm types and virulence genotypes, suggesting clonal dissemination and horizontal gene transfer.

Conclusions:

  • Macrolide-resistant S. pyogenes strains are prevalent in asymptomatic carriers, particularly children.
  • Specific lineages and virulence genes contribute to the success and spread of these resistant strains.
  • The presence of transferable resistance and virulence genes highlights the potential for further dissemination and impact on public health.

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