Antibiotic susceptibility of Group A Streptococcus isolated from throat swab culture of school children in Pokhara, Nepal

Group A Streptococcus (GAS) or Streptococcus pyogenes is estimated to be present in 5.0-15.0% of normal individual in the respiratory tract, vagina, skin and anus without any sign of disease. This study was carried out to find out the rate of asymptomatic throat carriage of S. pyogenes and antibiotic susceptibility of the isolates in school children of Pokhara, Western Nepal. A total of 487 randomly selected children younger than 16 years were included in the study. Throat swabs collected were subjected to 5.0% Sheep blood agar supplemented with crystal violet (CVBA).GAS was identified by â-haemolytic colonies, bacitracin sensitivity, cotrimoxazole resistivity, catalase negativity and PYR positivity. Antibiotic susceptibility test was performed on Muller Hinton agar (MHA) containing 5% sheep blood by modified Kirby-Bauer disc diffusion method. Out of total 487 throat swabs, GAS was isolated in 9.2% ( n=45). Among the isolates, 46.6% (n=21) were from male children where as 53.4% (n=24) from female children. There was no significant sex difference in colonization of GAS (p>0.05). Out of 45 isolates, 100.0% isolates were sensitive to antibiotic penicillin-G and amoxycillin where as 15.6%, 6.6%, and 2.2% isolates were resistant to antibiotic erythromycin, tetracycline and azithromycin respectively.