Circulating serotypes and antimicrobial sensitivity of Streptococcus pyogenes isolates from children in Cyprus

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• Group A Streptococcus (GAS) is a significant bacterial pathogen causing pharyngitis and scarlet fever in children.
• T-serotyping is a method used to classify GAS strains based on M protein.
• Antibiotic resistance patterns in GAS are crucial for effective treatment and public health surveillance.

Purpose of the Study:

• To determine the prevalent T-serotypes of Group A Streptococcus causing pharyngitis and scarlet fever in Cypriot children.
• To investigate the antibiotic susceptibility profiles of these GAS isolates, focusing on penicillin, clindamycin, erythromycin, and tetracycline.
• To explore the potential correlation between macrolide antibiotic consumption and observed macrolide resistance rates.

Main Methods:

• Collection and laboratory analysis of 88 Group A Streptococcus isolates from pharyngeal samples of children over a 14-month period.
• Identification of GAS T-serotypes using established microbiological techniques.
• Antimicrobial susceptibility testing (AST) for penicillin, clindamycin, erythromycin, and tetracycline.
• Estimation of macrolide consumption using defined daily doses (DDD) per 1000 inhabitants per day.

Main Results:

• The most common T-serotypes identified were T28 (25%), T8/25/Imp19 (22.7%), and T12 (9.1%).
• All 88 isolates were susceptible to penicillin and clindamycin.
• Resistance was observed in 1.1% for erythromycin and 18.2% for tetracycline.
• Macrolide consumption was low (1.7 DDD/1000 inhabitants/day).

Conclusions:

• T-serotype distribution of GAS in Cypriot children shows specific prevalent types.
• Penicillin and clindamycin remain effective treatment options for GAS infections in this population.
• The low rate of macrolide resistance may be associated with limited macrolide antibiotic usage, highlighting the importance of antibiotic stewardship.