Reemergence of Chloramphenicol Sensitivity among Salmonella enterica serovars Typhi and Paratyphi : a six year experience in a tertiary care hospital in Nepal

Abstract

Emerging drug resistance among Salmonella Typhi and Paratyphi has become challenging in the treatment of enteric fever. The objective of this study was to determine the antibiotic susceptibility pattern of Salmonella serotypes isolated from patients with enteric fever admitted to Manipal Teaching Hospital, Pokhara,Nepal. A total of 30 Salmonella enterica serovar Typhi, Paratyphi A, and Paratyphi B isolated from cases of typhoid and paratyphoid fever admitted to Manipal Teaching Hospital over a period from January 2012 to March 2018 were investigated. All strains were identified by standard microbiological methods and tested for in vitro antibiotic susceptibility testing,using Kirby-Bauer disc diffusion method following the criteria designed by the Clinical and Laboratory Standards Institute (CLSI 2013). S Typhi was the most predominant amongst all the isolates (18 of 30 i.e. 60%), followed by S Paratyphi A (33.3%, 10 out of 30) and S Paratyphi B (6.6%; 2 out of 30). Overall, 91.3% of the isolates were susceptible to chloramphenicol. The percentage sensitivities towards ceftriaxone, ciprofloxacin, cotrimoxazole and ampicillin were 82.6%, 75.8%, 63% and 37% respectively. All the isolates were sensitive to imipenem and amikacin. These findings suggested that there were changing patterns of antibiotic resistance in enteric fever with reemergence of chloramphenicol sensitive Salmonellae. This necessitates continuous surveillance of cases and re-evaluation of chloramphenicol therapy in Salmonella infections in Nepal.