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Resistance to macrolides in Streptococcus pyogenes in France in pediatric patients
1Service de Microbiologie, Hôpital Robert Debré, 75019 Paris, France. edouard.bingen@rdb.ap-hop-paris.fr
Abstract:
A total of 1,500 recent throat isolates of Streptococcus pyogenes collected between 1996 and 1999 from children throughout France were tested for their susceptibility to erythromycin, azithromycin, josamycin, clindamycin, and streptogramin B. The erythromycin-resistant isolates were further studied for their genetic mechanism of resistance, by means of PCR. The clonality of these strains was also investigated by means of serotyping and ribotyping. In all, 6.2% of the strains were erythromycin resistant, and 3.4 and 2.8% expressed the constitutive MLS(B) and M resistance phenotypes and harbored the ermB and mefA genes, respectively; ermTR was recovered from one isolate which also harbored the ermB gene. Ten serotypes and 8 ribotypes were identified, but we identified 17 strains by combining serotyping with ribotyping. Among the eight ribotypes, the mefA gene was recovered from six clusters, one being predominant, while the ermB gene was recovered from four clusters, of which two were predominant.
Insights
6.2% of Streptococcus pyogenes strains from French children showed erythromycin resistance. Genetic analysis revealed ermB and mefA genes as primary resistance mechanisms, with distinct clonalities observed.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Streptococcus pyogenes is a significant bacterial pathogen causing various infections in children.
- Antibiotic resistance in S. pyogenes is a growing public health concern, necessitating continuous surveillance.
- Macrolide resistance, particularly to erythromycin, is a key challenge in treating S. pyogenes infections.
Purpose of the Study:
- To determine the prevalence of antibiotic resistance in recent S. pyogenes throat isolates from children in France.
- To investigate the genetic mechanisms and clonal dissemination of erythromycin-resistant S. pyogenes strains.
Main Methods:
- Susceptibility testing against erythromycin and other antibiotics.
- Polymerase Chain Reaction (PCR) to identify resistance genes (ermB, mefA, ermTR).
- Serotyping and ribotyping to assess strain clonality.
Main Results:
- 6.2% of 1,500 S. pyogenes isolates exhibited erythromycin resistance.
- Constitutive MLS(B) and M resistance phenotypes were found in 3.4% and 2.8% of strains, respectively, linked to ermB and mefA genes.
- Ten serotypes and eight ribotypes were identified, with mefA and ermB genes associated with specific ribotype clusters.
Conclusions:
- Erythromycin resistance in S. pyogenes is present in French pediatric populations.
- The ermB and mefA genes are the predominant genetic determinants of macrolide resistance.
- Clonal spread, as indicated by ribotyping, plays a role in the dissemination of resistant S. pyogenes strains.