The rate of asymptomatic throat carriage of Streptococcus pyogenes and its associated risk factors among Kabul University students

Abstract

Streptococcus pyogenes (S. pyogenes) is the main agent of acute pharyngitis and skin infections that may result in the late complications of glomerulonephritis and rheumatic fever. Infection with streptococcus group A is a global health problem, which is most common in children and adults. This study was conducted to investigate the rate of S. pyogenes throat carriers and its main risk factors among healthy students of Kabul university. In the present study pharyngeal swabs of 260, [155 (59.6%) were male and 105 (40.4%) were female] asymptomatic university students aged between 19-30 years, were collected and immediately transported to the laboratory for detection of S. pyogenes following standard microbiological procedures. Production of beta hemolytic colonies on blood agar, sensitivity to bacitracin antibiotic, gram stain positivity, catalase negativity test and streptococcal grouping latex kit (ProlexTM) tests were used to identify and differentiate S. pyogenes from other streptococcus spp. Statistical analysis of data was performed using SPSS 21, Chi-square and Logistic regression tests were applied for the categorical data analysis. A P value equal to or less than 0.05 was considered statistically significant. Totally 61 (23.5%) beta hemolytic streptococci were isolated from 260 samples. Among 61 beta hemolytic isolates, 44 (16.9%) were identified as S. pyogenes. The colonization rate of S. pyogenes was higher in male 25 (56.8%) than female 19 (43.2%), which was not statistically significant (p=0.678). Age, residence of the students at hostel and shared utensil use were not statistically significant (p=0.088, p= 0.449, p=0.241 respectively), but the number of children in the family was an important risk factor. People with 1-3 children had a 23-fold higher risk (p˂0.05), and people with 4-6 children had a 27-fold higher risk of carrying S. pyogenes, than those who did not had any children (p˂0.05). In the present study the asymptomatic throat carriage rate of S. pyogenes among Kabul University students, was high. Among all risk factors the number of children in the family was significantly associated with S. pyogenes throat carriage.