Antimicrobial susceptibilities of enteric bacterial pathogens isolated in Kathmandu, Nepal, during 2002-2004.

Introduction: The prevalence and antimicrobial susceptibility patterns of the bacterial enteropathogens Vibrio cholerae, Salmonella species and Shigella species were investigated.

Methodology: A total of 877 stool samples were received for culture at the National Public Health Laboratory (NPHL), Kathmandu, Nepal, during January 2002 to December 2004, from diarrhoea patients attending Shukraraj Tropical Infectious Hospital and referral outpatients. All samples collected were processed for isolation and antibiotic susceptibility testing of Vibrio cholerae, Salmonella spp. and Shigella spp.

Results: Of the 877 stool samples, 148 (16.8%) were culture positive for one of the three bacterial enteropathogens investigated. Among them, Vibrio cholerae, Shigella spp. and Salmonella spp. accounted for 98/877 (11.1%), 41/877 (4.6%), 9/877 (1.02%) of the isolates respectively. A year-to-year variation was seen in the type of predominant organism, with Shigella spp. being the most prevalent in 2002 and 2003 and Vibrio spp. in 2004. In all three years, Vibrio cholerae were encountered only during the months of April to June while Salmonella spp. and Shigella spp. were isolated throughout the whole year. All Vibrio cholerae and Salmonella isolates were susceptible to ciprofloxacin.  All Shigella isolates were susceptible to ceftriaxone. Ciprofloxacin resistance was observed among isolates of Shigella dysenteriae type-1 isolated after 2003.

Conclusion: Vibrio cholerae, Salmonella and Shigella infections are prevalent in Kathmandu, Nepal. A gradual increase in resistance to commonly used antimicrobials was seen among bacterial enteropathogens. Antimicrobial resistance surveillance is necessary to guide empirical treatment.