Susceptibility to Fluoroquinolones among Salmonella Enterica Serovars in Blood Culture

Abstract

Background and Aim: Enteric fever is a severe bloodstream infection contributing to higher rate of morbidity and mortality around the globe caused by S. Typhi and Paratyphi A. Fecal-oral route is the prevalent transmission route of enteric fever that manifests with various clinical outcomes such as nausea, fever, transient rash, chills, hepatosplenomegaly, abdominal discomfort, and malaise. Assessment of susceptibility to fluoroquinolones in Salmonella enterica serovars in blood cultures was the prime objective of the current study.

Methodology: This cross-sectional study was carried out on 326 suspected enteric fever patients attending the outpatient department of HBS Dental and General Hospital, Islamabad for the duration from July 2021 to June 2022.  Prior to study conduction, ethical approval for the study was taken and each individual signed the written informed consent. BACTEC culture bottles were used for the incubation of blood. Standard procedures were followed to identify the bacterial growth in the obtained isolates from the vials. Salmonella enterica serotyping of identified isolates was done. Salmonella Typhi and Salmonella Paratyphi isolation and identification were processed. All the isolates were then subjected to Kirby-Bauer disc diffusion method for antibiotic susceptibility test. Clinical Laboratory Standards Institute guidelines were used for the interpretation of results. All the data from laboratory analysis were analyzed in SPSS version 25.

Results: Of the total 326 suspected enteric fever patients, the incidence of positive Salmonella enterica was found in 28 (8.6%), out of which Salmonella Typhi and Salmonella Paratyphi A were 15 (54%) and 13 (46%) respectively. Salmonella enterica growth was not observed in patients with age>51 years. However, patients of age group 11-20 years and 21-30 years showed higher proportion of Salmonella enterica growth. Male patients had higher Salmonella enterica growth than females. All the isolates of Salmonella enterica exhibited resistance to ampicillin and nalidixic but sensitivity to chloramphenicol and ceftriaxone. The Salmonella Paratyphi A and Salmonella Typhi isolates presented reduced susceptibility to ofloxacin and ciprofloxacin.

Conclusion: The present study found that reduced susceptibility and higher level of resistance to fluoroquinolones are the major reasons for not considering the fluoroquinolones as a treatment option for Salmonella infections. Ceftriaxone is still the better drug choice in Salmonella Typhi and Paratyphi A.

Keywords: Fluoroquinolones, Salmonella Typhi, Salmonella Paratyphi, Enterica serovars, Blood culture