# Current Antimicrobial Susceptibility Trends and Clinical Outcomes of Typhoidal Salmonella in a Large Health Authority in British Columbia, Canada

## TL;DR

This study examines drug-resistant typhoidal Salmonella cases in British Columbia and finds that ciprofloxacin resistance is high, while multi-drug resistance remains rare.

## Contribution

The study provides updated antimicrobial susceptibility trends for typhoidal Salmonella in British Columbia, emphasizing ciprofloxacin resistance.

## Key findings

- MDR typhoidal Salmonella was rare (1.5%) with no XDR cases observed.
- Ciprofloxacin resistance reached 96% in 2024, while other antimicrobials showed high susceptibility.
- Three percent of patients experienced infection relapse within 30 days.

## Abstract

Background: From 2018 to 2021, travel-related extensively drug-resistant (XDR) Salmonella Typhi was identified in Ontario, Canada. Opportunities remain to characterize typhoidal Salmonella antimicrobial susceptibility trends (including multi-drug resistance phenotypes; MDR) within a large health authority in British Columbia, Canada. Methods: This retrospective study included patients with Salmonella Typhi or Paratyphi A, B or C bacteremia identified at Fraser Health regional microbiology laboratory from 2018 to 2024. The primary outcome was the proportion of cases with MDR and XDR typhoidal Salmonella. Secondary outcomes included annual antimicrobial susceptibility for ampicillin, ceftriaxone, ciprofloxacin, trimethoprim-sulfamethoxazole, ertapenem, meropenem and azithromycin. Clinical outcomes included hospitalization length, and 30-day mortality, clinical cure and infection relapse. Results: Among 271 patients, most were previously healthy and recently travelled. There were extended spectrum beta-lactamase (1.1%) and MDR (1.5%) typhoidal Salmonella, with no XDR cases observed. In 2024, ciprofloxacin resistance was 96% while susceptibility rates were high for other studied antimicrobials. Within 30 days, no deaths were reported; however, six patients (3%) had infection relapse. Conclusions: Currently, in British Columbia, MDR typhoidal Salmonella remains rare. Empiric ciprofloxacin should be avoided due to persistently high resistance rates. With ongoing travel patterns, it is beneficial for institutions to continue typhoidal Salmonella antimicrobial susceptibility surveillance, and travelers should seek pre-travel health assessments.