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

Abstract

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 microg/mL (range, 0.125-8 microg/mL), and MIC90 was 8 microg/mL (range, 0.125-8 microg/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 microg/mL (range, 0.125-32 microg/mL) and 2 microg/mL (range, 0.25-8 microg/mL) respectively. All isolates were sensitive to penicillin G and chloramphenicol on disc diffusion test. However, their MIC50 was 0.032 microg/mL (range, 0.012-0.125 microg/mL) and 2 microg/mL (range, 0.25-4 microg/mL) respectively.

Conclusion: High prevalence of antimicrobial resistance found among GABHS needs a longitudinal surveillance of isolates from different centers in India.