Serotyping and antibiotic resistance profile of common bacterial isolates causing gastroenteritis.

Thesis Report.

Abstract: Gastroenteritis is one of the major problems throughout the world and responsible for high morbidity in developing countries like Nepal and comes in the second position among top ten diseases of the world. The main objective of the study was to found out etiological agents and serotyping and antibiotic resistance profile of different bacterial isolates retrieved from the diarrhoeal stool samples of patients visiting National Public Health Laboratory, Teku, Kathmandu, Nepal. The study was carried out during the period of April 2015 to November 2015. A total 383 stool samples were collected in laboratory or brought from the outbreak area on Cary-Blair medium. The stools samples were inoculated for enrichment in alkaline peptone water and on selenite F broth as required and incubated for 4-6 hours. Then the samples from enrichment media were culture on TCBS for Vibrio species and on S-S agar for Salmonella and Shigella species. From TCBS and S-S agar, growth was cultured on Mac-Conkey agar and Nutrient agar. All the bacterial isolates were identified by biochemical and serological test. Antibiotic susceptibility test was performed by modified kriby Bauer disc diffusion tests. Of 383 samples,111 (29%) were positive for growth. Of these isolates, 82 (22.2%) were Vibrio cholera O1 serogroup, 81 were ogawa serotype and 1 was inaba. All V. cholera isolates were El Tor serotype. Shigella species 25 (6.5%), and Salmonella species 4 (1%) were also isolated. V. cholera were 100% resistant to cotrimoxazola, furazolidine, nalidixic acid and most of them were susceptible to ceftriaxone, azithromycin, ciprofloxacxin and tetrecycline. Shigella species were highly resistant to amoxicillin/clavulanic acid, ampicillin/sulbactam, amikacin, gatifloxacin, ofloxacin, and meropenem and most of them were susceptible to ceftriaxone. The Salmonella species were 100% susceptible to ampicillin and ciprofloxacin. The bacterial isolates were found to be resistant to many antibiotics so that selection of antibiotic should be based on susceptibility testing.