Trends in Group A <i>Streptococcus</i> Isolation and Antimicrobial Susceptibility in a Pediatric Population (2021–2023): Comparison with Six Previous Surveys

Group A Streptococcus (GAS) is a major pathogen of respiratory infections in children. This study investigated recent trends in antimicrobial susceptibility among GAS isolates in our hospital and compared them with past data. Between 2021 and 2023, 195 GAS isolates were obtained from 195 pediatric patients. Minimum inhibitory concentrations (MICs) of 22 antimicrobial agents were determined using the broth microdilution method. Susceptibility was categorized as susceptible (S), intermediate (I), or resistant (R) according to the Clinical and Laboratory Standards Institute criteria and compared with six previous surveys (1996-2018; total 1,871 isolates). The number of isolates was low in 2021-2022 but increased sharply in 2023 (n=157). Most isolates were from throat swabs, and the median age was 5 years (range: 1-15 years). Resistance (I + R) rates were as follows: azithromycin (20%), erythromycin (19%), clarithromycin (19%), tetracycline (8%), and clindamycin (4%). Erythromycin resistance increased from 9% in 1996 to 58% in 2013 but declined to 19% in this study. No β-lactam resistance was previously observed; however, two isolates (1%) showed elevated MICs to cefalexin, suggesting reduced susceptibility. These findings underscore the importance of continued monitoring of GAS isolation trends and antimicrobial resistance, including emerging β-lactam reduced susceptibility.