Antibiotic resistance pattern of group-a beta-hemolytic streptococci isolated from north Indian children

Background: The current resistance pattern of GABHS (group-A beta-hemolytic streptococci) in India has not been discussed.
Aim: To fill the above-mentioned void, we planned this study to determine the prevalence and degree of antibacterial resistance in GABHS isolates.
Settings and Design: Children with acute pharyngo-tonsillitis who had not received antibiotic in the preceding week, attending the pediatric OPD, were prospectively enrolled over a period of 1 year. Throat swabs were collected from each child and transported to microbiology laboratory, as early as possible.
Materials and Methods: A throat swab culture for GABHS was done. All GABHS were subjected to antibiotic susceptibility and minimum inhibitory concentration (MIC) test according to Clinical Laboratory Standard Institute (CLSI) guidelines.
Results: In the present study, 12.6% (55/435) of the children with acute pharyngo-tonsillitis had throat swab culture positive for GABHS. The prevalence of macrolide resistance was 10.2%. The MIC50 for macrolide-resistant strain was 0.5 µg/mL (range, 0.125-8 µg/mL), and MIC90 was 8 µg/mL (range, 0.125-8 µg/mL). Tetracycline and co-trimoxazole resistances were 24.5% and 12.2% respectively. The values of MIC50 for tetracycline- and co-trimoxazole-resistant strains were 4 µg/mL (range, 0.125-32 µg/mL) and 2 µg/mL (range, 0.25-8 µg/mL) respectively. All isolates were sensitive to penicillin G and chloramphenicol on disc diffusion test. However, their MIC50 was 0.032 µg/mL (range, 0.012-0.125 µg/mL) and 2 µg/mL (range, 0.25-4 µg/mL) respectively. Conclusion: High prevalence of antimicrobial resistance found among GABHS needs a longitudinal surveillance of isolates from different centers in India.

Keywords
Group-A beta-hemolytic streptococci, pharyngo-tonsillitis, streptococcus hemolyticus