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[Emergence of resistance to macrolides in Streptococcus pyogenes]
C Vinagre1, M Cifuentes, F Valdivieso
1Unidad de Microbiología Oriente, Facultad de Medicina, Universidad de Chile, Santiago de Chile. gtomasel@chilesat.net
Background:
Diseases produced by Streptoccocus pyogenes are still a problem in Chile, as in the rest of the world. It exhibits in vitro susceptibility to different antimicrobials, but penicillin continues to be the treatment of choice. Alternative drugs have been developed for allergic patients, such as erythromycin, new macrolides and cephalosporins. Nevertheless, resistant strains are appearing due to the indiscriminate use of macrolides.
Aim:
To assess present antimicrobial susceptibility of S Pyogenes strains isolated from chilean patients.
Material And Methods:
The susceptibility to penicillin, macrolides, clindamycin, cephalotin and vancomycin of 153 S Pyogenes strains, obtained from different health centers of the Metropolitan Region and isolated between 1996 and 1998, was assessed using the Kirby-Bauer method. Agar dilution minimal inhibitory concentration was then determined to macrolide resistant strains.
Results:
All strains were susceptible to penicillin. There was a 7.2% cross-resistance to macrolides.
Conclusions:
These results confirm that S Pyogenes resistance to macrolides has increased considerably in the Metropolitan Region of Chile during the last years.
Insights
Streptococcus pyogenes infections remain a concern, with increasing macrolide resistance observed in Chile. Penicillin remains effective, but macrolide resistance necessitates monitoring alternative treatments for bacterial infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Context:
- Streptococcus pyogenes causes significant diseases globally and in Chile.
- Penicillin is the primary treatment, but macrolides are alternatives for allergic patients.
- Indiscriminate macrolide use has led to the emergence of resistant strains.
Purpose:
- To evaluate the current antimicrobial susceptibility patterns of Streptococcus pyogenes.
- To assess S. pyogenes strains isolated from Chilean patients between 1996 and 1998.
Summary:
- A study assessed 153 S. pyogenes strains using Kirby-Bauer and agar dilution methods.
- All tested strains remained susceptible to penicillin.
- A notable 7.2% cross-resistance to macrolides was identified, indicating increased resistance.
Impact:
- Confirms a significant increase in macrolide resistance among S. pyogenes in Chile's Metropolitan Region.
- Highlights the need for ongoing surveillance of antimicrobial resistance patterns.
- Informs clinical decisions regarding antibiotic selection for S. pyogenes infections.