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Updated: Jul 16, 2026
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Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Emergence of a novel macrolide-resistant Streptococcus pyogenes emm53 strain
L Strakova1, J Motlova, V Jakubu
1National Reference Laboratory (NRL) for Streptococci and Enterococci, National Institute of Public Health, Prague, Czech Republic. lenka.strakova@szu.cz
Summary
A specific clone of erythromycin-resistant group A Streptococcus (GAS) was prevalent in the Czech Republic in 2003. This clone, identified as emm53/ST340, showed distinct genetic characteristics compared to other GAS strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- Group A Streptococcus (GAS) is a significant human pathogen.
- Erythromycin resistance in GAS is an emerging public health concern.
- Specific GAS clones can dominate and cause invasive infections.
Purpose of the Study:
- To characterize an unusual emm53, T-28/T-non-typeable, iMLS(B) phenotype clone of GAS.
- To investigate the clonal diversity and genetic relatedness of invasive erythromycin-resistant GAS isolates in the Czech Republic.
- To trace the potential evolutionary history of the dominant emm53/ST340 clone.
Main Methods:
- Analysis of invasive erythromycin-resistant GAS isolates from the Czech Republic (2001-2004).
- Pulsed-field gel electrophoresis (PFGE) for clonal analysis.
- Multilocus sequence typing (MLST) to determine sequence types (STs).
Main Results:
- A specific emm53/ST340 clone constituted 28.6% of invasive erythromycin-resistant GAS isolates in 2003.
- All emm53 isolates shared identical PFGE patterns, irrespective of invasiveness or tetracycline resistance.
- The emm53/ST340 isolates showed significant genetic divergence from the original Lancefield emm53/ST11 isolate.
Conclusions:
- The emm53/ST340 clone represents a distinct and successful lineage of invasive erythromycin-resistant GAS.
- This clone has undergone genetic changes, differentiating it from earlier emm53 strains.
- Understanding the emergence and characteristics of such clones is crucial for monitoring GAS epidemiology.
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