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Erythromycin resistance genes in Streptococcus pyogenes isolates in Kanagawa, Japan
T Murase1, R Suzuki, Y Watanabe
1Department of Bacteriology and Pathology, Kanagawa Prefectural Public Health Laboratory, Yokohama, Japan. murase@muses.tottori-u.ac.jp
Abstract:
The susceptibility of 224 Streptococcus pyogenes isolates obtained from children in Japan from 1981 to 1997 to treatment with erythromycin was determined by the agar dilution method. A total of 17 isolates belonging to serotype M12T12 were resistant (MICs>1 microg/ml). Fourteen of the 17 resistant strains obtained from 1982 to 1985 harbored ermB and showed an identical pulsed-field gel electrophoresis pattern, indicating the spread of a single clone. Two ermTR-containing isolates were obtained in 1983. mefA gene was found in a strain obtained in 1994 in the present study, although this gene is predominantly associated with recent erythromycin resistance among S. pyogenes strains in many countries.
Insights
Erythromycin resistance in Streptococcus pyogenes isolates from Japanese children was studied. A single clone carrying the ermB gene spread between 1982-1985, while other resistance genes were also detected.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Streptococcus pyogenes is a significant human pathogen.
- Erythromycin resistance in S. pyogenes is a growing public health concern.
- Understanding resistance mechanisms and their evolution is crucial for effective treatment.
Purpose of the Study:
- To determine the susceptibility of S. pyogenes isolates from Japanese children to erythromycin.
- To investigate the genetic basis and epidemiological spread of erythromycin resistance.
- To track the emergence of different resistance genes over time.
Main Methods:
- Agar dilution method was used to assess erythromycin susceptibility.
- Pulsed-field gel electrophoresis (PFGE) was employed to analyze genetic relatedness of resistant strains.
- Molecular techniques were used to identify specific resistance genes (ermB, ermTR, mefA).
Main Results:
- Out of 224 S. pyogenes isolates, 17 (serotype M12T12) showed resistance to erythromycin (MICs > 1 microg/ml).
- Fourteen resistant isolates from 1982-1985 harbored ermB and exhibited identical PFGE patterns, suggesting clonal spread.
- Two ermTR-containing isolates were identified in 1983, and a mefA gene was detected in a 1994 isolate.
Conclusions:
- A specific clone of S. pyogenes carrying ermB disseminated among children in Japan during the mid-1980s.
- The study highlights the dynamic nature of erythromycin resistance in S. pyogenes, with different resistance mechanisms emerging over time.
- The presence of mefA in a later isolate suggests its potential increasing prevalence in Japan, mirroring trends elsewhere.