Shigellosis in Nepal: 13 years review of nationwide surveillance.

BACKGROUND: Shigella is a major cause of gastroenteritis especially in children. In developing countries, the incidence is frequent and results are often life threatening. Changing epidemiology and emerging antibiotic resistance warrants continuous monitoring of susceptibility. The present study highlights the changing epidemiology and drug resistance patterns of Shigella isolated at different hospitals of Nepal over a period of 13 years (Jan. 2003-Dec. 2015).

METHODS: This study was carried out in 12 participating laboratories. Stool specimens received at respective laboratories were processed for isolation and identification of Shigella species and confirmed by serotyping at National Public Health Laboratory. Antimicrobial resistance patterns were determined by Kirby Baeur disc diffusion test.

RESULTS: A total of 332 isolates were identified as Shigella species of which Shigella flexneri (50 %) was the predominant serotype. Shigella dysenteriae, Shigella sonnei, Shigella boydii, and untypable Shigella spp. respectively, accounted for 28.6, 27.54, 10.2, 4.5, and 6.6 % of the total number. Change in prevalent serotype is noted over the years. S. dysenteriae was the prevalent species in Nepal in 2003 and 2004, but since 2005, S. flexneri remained prevalent. Majority of the isolates were recovered from children aged 1-10 years and was statistically significant (p = 0.023) compared to the other age groups. High resistance among all Shigella species to the first-line drugs like ampicillin (88 %), cotrimoxazole (76 %), ciprofloxacin (39 %,) and nalidixic acid (80 %) was observed; 46.1 % of total isolates were multidrug resistant (MDR), and the most common MDR profile was ampicillin, nalidixic acid, and co-trimoxazole. Prevalence of MDR increased significantly in 2010 as compared to 2003. Only few Shigella isolates were resistant to ceftriaxone.

CONCLUSIONS: The study revealed S. flexneri as the predominant serogroup in Nepal. Children below 10 years were more prone to the disease. Nalidixic acid, ampicillin, co-trimoxazole, and ciprofloxacin should not be used empirically as the first-line drugs in treatment of shigellosis. Since the distribution of different species of Shigella and their antibiotic susceptibility profile may vary from one geographical location to another and may also change with time, continuous local monitoring of resistance patterns is necessary for appropriate antimicrobial therapy.