Change in antimicrobial resistance pattern of Salmonella Typhi in central India

Multidrug resistant Salmonella Typhi infections have been reported worldwide in the last decade. In a study from central India in 1991 multidrug resistant S. Typhi were reported to account for 91 per cent of patients of enteric fever. The present study was planned to study the antimicrobial susceptibility pattern, phage types and biotypes of strains of S. Typhi prevalent in this region.

A total of 54 isolates of Salmonella were recovered from 1468 blood samples of patients suspected to have enteric fever and admitted in the Government Medical College and Hospital, Nagpur. Antimicrobial susceptibility pattern of these isolates was studied by disc diffusion test. Phage typing and biotyping of the first 33 strains was done at the National Salmonella Phage Typing Center, New Delhi. Minimum inhibitory concentration of chloramphenicol was determined by agar dilution method.

Of 54 isolates of Salmonella, 51(94%) were S. Typhi and 3 (6%) were S. paratyphi A serotype. Of the 30 isolates of S. Typhi subjected to phage typing, two phage types E1 23 (77%) and A 7 (23%) were found to be prevalent in this region. Multidrug resistance was observed in 12 (22%) strains of S. Typhi. Thirty five (68%) strains were sensitive to chloramphenicol, ampicillin, gentamicin, cotrimoxazole, cefotaxime and ciprofloxacin. Resistance to two antibiotics was observed in 4 (8%) strains. Cefotaxime resistance was observed in one isolate and gentamycin resistance in two, while none of the isolates was found to be ciprofloxacin resistant.

Multidrug resistance in S. Typhi has decreased from that reported in 1991 though there is a still a small percentage of strains which continue to be multidrug resistant.