Isolation & antimicrobial susceptibility of Shigella from patients with acute gastroenteritis in western Nepal

Background & objectives: Shigellae play an important role as a causative organism of acute gastroenteritis, which is a global health problem with significant morbidity and mortality in especially in developing countries. This study was carried out to determine the isolation and pattern of antimicrobial resistance of Shigella in patients with acute gastroenteritis in western Nepal. Methods: The study included all patients with acute gestroenteritis who visited a tertiary care hospital at Pokhara, Nepal during a 2-year period (2002-2004). The isolates was confirmed as Shigella by biochemical reaction and slide agglutination test using specific antisera. Antibiotic sensitivity test was determined by agar diffusion method and minimum inhibitory concentration (MIC) of the drugs was detected. Results: Of the 770 stool samples, 83 (10.8%) yielded Shigella. Shigella flexneri caused 56 (67.4%) of the total cases of shigellosis followed by S. dysenteriae 12 (14.5%), S. sonnei 10 (12%) and S. boydii 5 (6%). Of the 83 isolates, 67 (80.7%) showed resistance to various drugs and 62 (74.7%) were resistant to two or more drugs. Resistance to cotrimoxazole was 80.7 per cent followed by tetracycline 74.7 per cent, ampicillin 53.0 per cent, nalidixic acid 31.3 per cent and ciprofloxacin 2.4 per cent. The MIC₅₀ and MIC₉₀. values of those drugs were also very high. All isolates were sensitive to cefotaxime and ceftriaxone. Interpretation & conclusion: The findings of our study suggested that Shigellae was an important etiological agent for acute gastroenteritis, with a high rate of drug resistance and requires constant monitoring in this region.