Antibiotic Resistance among Salmonella Isolates - A Five-year Trend

Abstract

In India, enteric fever is an endemic febrile illness, caused by Salmonella enterica serovar Typhi/ Paratyphi A, B, and C. The incidence of Salmonella enterica serovar Typhi/ Paratyphi isolates with decreased susceptibility/ resistance to fluoroquinolones is very high, though these isolates have been reported to be sporadically resistant to third-generation cephalosporins. This retrospective study was planned to analyse the trends of drug resistance along with the emergence of ceftriaxone resistance, if any, among Salmonella enterica isolates. Materials and Methods:This retrospective study in a tertiary care hospital over a span of five years (2018)(2019)(2020)(2021)(2022). All the blood specimens were inoculated in blood culture bottles and were processed using automated systems as per standard protocols. All the isolates obtained were identified and their antimicrobial susceptibility pattern was determined using VITEK 2.Results: A total of 1083 S. enterica were isolated, of which, 779 (71%) were Salmonella Typhi, and 304 (29%) were Salmonella Paratyphi A. The positivity of blood culture for Salmonella enterica varied from 0.7% to 1.3%. The distribution of S. Typhi (70%-80%) and S. Paratyphi (20%-30%) remained almost uniform during all the years. A significant increase in ciprofloxacin resistance was observed in S. Typhi isolates in all the years. 0.7%-3.2% and 1.1%-1.4% of S. Typhi and S. Paratyphi A isolates, respectively, were found resistant to ceftriaxone over the years. Conclusion:A high resistance to fluoroquinolone among S. Typhi and S. Paratyphi A isolates was observed with the emergence of ceftriaxone resistance and re-emergence of susceptibility to first-line medications.