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Highly virulent M1 Streptococcus pyogenes isolates resistant to clindamycin.
C Plainvert1, C Martin2, J Loubinoux3
1Service de bactériologie, centre national de référence des streptocoques, groupe hospitalier universitaire Paris, centre Cochin-Hôtel Dieu-Broca, Assistance publique-Hôpitaux de Paris, Paris, France; Institut Cochin, université Sorbonne Paris Descartes, Paris, France; Inserm, U1016, Paris, France; CNRS (UMR 8104), Paris, France.
Medecine Et Maladies Infectieuses
|November 26, 2015
Summary
Highly virulent group A Streptococcus (GAS) emm1 strains resistant to clindamycin have emerged in France. This finding highlights the need for ongoing surveillance of invasive GAS to inform treatment guidelines.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Group A Streptococcus (GAS), particularly the emm1 type (Streptococcus pyogenes), is a primary cause of severe invasive infections like necrotizing fasciitis and streptococcal toxic shock syndrome.
- Standard treatment for severe invasive GAS infections involves a combination of clindamycin and penicillin.
- Historically, most emm1 GAS isolates have remained susceptible to clindamycin.
Purpose of the Study:
- To characterize the phenotypic and genotypic features of clindamycin-resistant emm1 GAS clones.
- To investigate the emergence of antibiotic resistance in a key pathogen responsible for invasive infections.
Main Methods:
- Analysis of 1321 invasive GAS isolates from 2011-2012.
- emm sequence typing, detection of pyrogenic exotoxin/superantigen genes.
- Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) for cluster analysis.
- Disk diffusion for antibiotic susceptibility testing and PCR for resistance gene detection.
Main Results:
- Fifty-two (3.9%) of the invasive GAS isolates exhibited clindamycin resistance.
- Seven of these resistant isolates were identified as emm1 type.
- All seven emm1 isolates shared identical genomic markers: erm(B) gene for macrolide resistance, emm subtype 1.0, consistent toxin/superantigen profiles, PFGE patterns, and MLST sequence types.
Conclusions:
- This study reports the first identification of highly virulent, clindamycin-resistant emm1 GAS isolates in France.
- The emergence of these resistant strains underscores the critical need for continuous epidemiological monitoring of invasive GAS.
- Such surveillance is essential for adapting and updating clinical treatment guidelines to effectively manage invasive GAS infections.
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