Antibiogram Profile of Salmonella enterica Serovar Typhi in India - A Two Year Study.

Typhoid fever continues to remain a major health problem in the developing world, and the emergence of multidrug-resistant (MDR) strains has further reduced therapeutic options for treatment of the disease. The National Salmonella and Escherichia Centre in Kasauli, India received 128 Salmonella Typhi isolates during 2008-2009. These were evaluated for antimicrobial resistance, prevalent resistotypes and the proportion of MDR strains, using standard methods for 11 antimicrobials. An abrupt decrease in the proportion of MDR strains was observed. Only 4.7% of the isolates were found to be MDR with resistotypes chloramphenicol-ampicillin-streptomycin-nalidixic acid-trimethoprim (C-AS-Na-Tr) and chloramphenicol-ampicillin-nalidixic acid-trimethoprim (C-A-Na-Tr), which is very low compared to other studies from India. Nalidixic acid resistance was found to be present in 93.8% of the isolates. Moreover, the difference in the mean minimum inhibitory concentration (MIC) of ciprofloxacin for nalidixic acid-resistant and nalidixic acid-sensitive strains was found to be statistically significant (p<0.001), which calls into question the further use of ciprofloxacin for the treatment of typhoid fever because of potential treatment failures. The low proportion of MDR strains increases the possibility of first-line drugs for the treatment of typhoid fever.