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

The current resistance pattern of GABHS (group-A beta-hemolytic streptococci) in India has not been discussed.

To fill the above-mentioned void, we planned this study to determine the prevalence and degree of antibacterial resistance in GABHS isolates.

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.

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.

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.

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