Rising prevalence of enteric fever due to multidrug-resistant Salmonella: an epidemiological study

A prospective study of the prevalent aetiology of enteric fever was undertaken at a tertiary care hospital in North India at intervals of every 3 years. Salmonella spp. were isolated from 174 (7%) patients. Amongst these, 140 (80%) patients were infected by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) and 16 (9%) by S. enterica serovar Paratyphi A; the remaining 11% were infected by other S. enterica serogroups, Typhimurium, Paratyphi C and Senftenberg, and other group E salmonella. A significantly greater number of S. Typhi were isolated in the summer and monsoon months. Multidrug resistance (resistance to chloramphenicol, ampicillin and co-trimoxazole) sequentially increased from 34% in 1999 to 66% in 2005. Increasing resistance was also noticed to the other antibiotics, especially to the cephalosporins. Moreover 8% of the S. Typhi isolates were found to be presumptive extended spectrum beta-lactamase producers. There was a gradual development of resistance to fluoroquinolones over the 7 years. No resistance was observed to fluoroquinolones in 1999, while in 2005 4.4% resistance was observed to sparfloxacin, 8.8% resistance to ofloxacin and a high resistance, 13%, to ciprofloxacin. This is an alarming development and it is of paramount importance to limit unnecessary use of fluoroquinolones and third generation cephalosporins so that their efficacy against salmonella is not jeopardized further.