Decline of erythromycin resistance of group A streptococci in Japan

Area of Science:

• Microbiology
• Infectious Diseases
• Pediatrics

Background:

• Group A Streptococcus (GAS) is a significant bacterial pathogen causing various infections in children.
• Understanding the serotypes and antibiotic resistance patterns of GAS is crucial for effective treatment and public health surveillance.
• This study examines GAS isolates from children over a decade to assess epidemiological trends.

Purpose of the Study:

• To serologically type Group A Streptococcus isolates from children with various infections.
• To determine the antibiotic susceptibility patterns of these GAS isolates over a 10-year period.
• To identify trends in antibiotic resistance, particularly for commonly used antimicrobials.

Main Methods:

• Serological typing was performed on 670 Group A Streptococcus isolates collected from children between 1981 and 1990.
• Antibiotic susceptibility testing was conducted for penicillin G, cephalexin, erythromycin, lincomycin, chloramphenicol, and tetracycline.
• Isolates were categorized based on clinical presentation: pharyngitis, scarlet fever, suppurative, and nonsuppurative infections.

Main Results:

• The most prevalent M serotypes identified were 12, 4, 1, 3, and 28.
• No resistance was observed to penicillin G and cephalexin among all 670 isolates.
• Resistance to erythromycin and lincomycin decreased significantly after 1983, with most resistant strains being M type 12.
• Chloramphenicol resistance mirrored erythromycin resistance trends, while tetracycline resistance declined from 60% to under 20%.

Conclusions:

• Penicillin G and cephalexin remain highly effective against Group A Streptococcus in this pediatric cohort.
• A notable decrease in erythromycin, lincomycin, and tetracycline resistance was observed over the study period.
• M serotype 12 was disproportionately associated with erythromycin resistance, highlighting the importance of serotype-specific resistance monitoring.