Is Antimicrobial Resistance Pattern of Enteric Fever Changing in Kathmandu Valley?

Introduction: Enteric fever is a public health problem in developing countries including Nepal. Antimicrobial sensitivity pattern of Salmonella sp causing enteric fever is changing over time and also differs according to geographical location. Periodic surveillance of antimicrobial resistance of Salmonella sp is mandatory for management of enteric fever rationally. The objective of this study was to analyze the resistance pattern of Salmonella sp to commonly used antimicrobials. Materials and Methods: This was a retrospective study undertaken reviewing the records of blood isolates of Salmonella sp over one year period at Kanti Children’s Hospital, Nepal. Antimicrobial sensitivity testing was done following Kirby Bauer’s disk diffusion technique using Muller Hinton agar. Results: Salmonella typhi was found to be 100% resistance to ampicillin and resistance to nalidixic acid and ciprofloxacin was also high. The resistance to chloramphenicol and ofloxacin was low. No resistance was found to amoxicillin, ceftriaxone, cefotaxime and amikacin. However, among the sensitive isolates of Salmonella typhi intermediate sensitivity to ceftriaxone and ceftazidime was reported to be high. Among the isolates of S paratyphi A, the resistance to nalidixic acid was 100% followed by 75% to ciprofloxacin. No resistance was found to chloramphenicol, ceftriaxone, cefixime, amikacin and low resistance to amoxicillin and ofloxacin. Among the sensitive isolates of S paratyphi A, majority of them were only moderately sensitive to cefotaxime and ceftazidime and about 1/3 of the organisms had only intermediate sensitivity to ceftriaxone. Conclusiion: Commonly used parenteral third generation cephalosporins, first line drugs like chloramphenicol and amoxicillin and ofloxacin among fluoroquinolones were found to be effective in vitro in treating enteric fever. However, Salmonella typhi was found to be highly resistant to the most frequently used drugs like ciprofloxacin and cefixime and Salmonella paratyphi A to ciprofloxacin. A comparative chart of antimicrobial sensitivity of enteric fever in children over 10 year period from different hospitals of Kathmandu valley is also presented in the study.