Related Experiment Videos
Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus
H A Lopardo1, M E Venuta, P Vidal
1Hospital de Pediatria Prof. Dr. Juan P. Garrahan, Universidad Católica Argentina, Buenos Aires, Buenos Aires, Argentina.
Abstract:
Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.
Insights
Penicillin-resistant Streptococcus pyogenes were not detected in Argentina studies. Erythromycin resistance in Streptococcus pyogenes was rare, affecting only 0.14-0.28% of isolates, with inducible resistance noted in most cases.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Streptococcus pyogenes is a significant human pathogen.
- Monitoring antibiotic susceptibility is crucial for effective treatment.
- Penicillin and erythromycin are key antibiotics for treating S. pyogenes infections.
Purpose of the Study:
- To determine the prevalence of penicillin and erythromycin resistance in Streptococcus pyogenes in Argentina.
- To investigate the mechanisms of erythromycin resistance.
Main Methods:
- Two cross-sectional studies conducted in May and October 1994.
- Involved 58 centers across 27 cities in Argentina.
- Antibiotic susceptibility testing using disk diffusion and agar dilution methods on 1072 (diffusion) and 595 (both methods) S. pyogenes isolates.
Main Results:
- No penicillin-resistant Streptococcus pyogenes isolates were identified (MIC100 = 0.03 µg/ml).
- Erythromycin resistance was observed in only four isolates (0.14% in May, 0.28% in October).
- Inducible resistance mechanisms were identified in three of the four erythromycin-resistant strains.
Conclusions:
- Penicillin remains highly effective against Streptococcus pyogenes in Argentina.
- Erythromycin resistance in S. pyogenes is currently low but warrants continued surveillance.
- Understanding resistance mechanisms is important for guiding antimicrobial therapy.