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Updated: Sep 26, 2026

Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
08:58

Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes

Published on: March 3, 2023

Predominance of two M-types among erythromycin-resistant group A Streptococci from Greek children

L Zachariadou1, J Papaparaskevas, I Paraskakis

  • 1Microbiology Department, 'Aghia Sophia' Children's Hospital, Athens, Greece.

Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
|April 2, 2003
PubMed

Insights

Erythromycin resistance in Streptococcus pyogenes clinical isolates from children in Greece was linked to specific M-serotypes, M22 and M84. These serotypes were predominantly associated with the Inducible Clindamycin Resistance (ICR) MLSB and Macrolide resistance (M) phenotypes.

Area of Science:

  • Microbiology
  • Clinical Infectious Diseases
  • Molecular Epidemiology

Background:

  • Streptococcus pyogenes (Group A Streptococcus) is a significant human pathogen.
  • Erythromycin resistance is a growing public health concern, impacting treatment options.
  • Understanding the genetic basis and epidemiological trends of antibiotic resistance in S. pyogenes is crucial.

Purpose of the Study:

  • To investigate the association between erythromycin resistance and specific M-serotypes in clinical isolates of S. pyogenes from children in Athens, Greece.
  • To characterize the resistance phenotypes of erythromycin-resistant S. pyogenes isolates.
  • To identify dominant M-serotypes among resistant S. pyogenes strains.

Main Methods:

  • Random selection of 49 erythromycin-resistant (EryR) and 21 erythromycin-susceptible (EryS) S. pyogenes isolates from a larger collection (n=1158).
  • M-serotyping of selected isolates.
  • Susceptibility testing for erythromycin, penicillin, vancomycin, and clindamycin.
  • Categorization into resistance phenotypes (M, Inducible Clindamycin Resistance MLSB [IR MLSB], Constitutive Clindamycin Resistance MLSB [CR MLSB]).

Main Results:

  • Erythromycin resistance was observed in 21% (248/1158) of S. pyogenes isolates.
  • All tested EryR and EryS isolates were susceptible to penicillin and vancomycin.
  • M22 (30%) and M84 (41%) were the dominant M-serotypes among EryR isolates.
  • M22 was most prevalent in the IR MLSB phenotype (65%), and M84 in the M phenotype (63%).
  • No predominant serotype was found in the susceptible group.

Conclusions:

  • Two distinct M-serotypes, M22 and M84, are highly represented among erythromycin-resistant S. pyogenes isolates in this pediatric population.
  • These M-serotypes are predominantly associated with specific resistance phenotypes (IR MLSB and M).
  • The findings highlight a potential link between specific M-serotypes and erythromycin resistance mechanisms in S. pyogenes, informing epidemiological surveillance and treatment strategies.

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