# Effect of COVID‐19 Pandemic on Epidemiology and Antimicrobial Susceptibility of Campylobacter Species, Salmonella enterica and Yersinia enterocolitica in Southwest Finland 2018–2022

## TL;DR

The study found that the COVID-19 pandemic reduced the spread of certain gut bacteria in Finland and limited antibiotic resistance, with travel being a key source of infection.

## Contribution

The study reveals how pandemic lockdowns impacted the spread and resistance patterns of specific gut bacteria in a specific geographic region.

## Key findings

- Travel-associated S. enterica and Campylobacter spp. cases dropped sharply during the pandemic and have since recovered slowly.
- Lockdowns reduced diagnosed enteropathogens and limited the emergence of resistant strains.
- Travel remains the primary source of S. enterica infections in Finland.

## Abstract

This study investigated the effect of the COVID‐19 pandemic on the epidemiology and antimicrobial susceptibility of fecal Campylobacter spp., Salmonella enterica
, and
Yersinia enterocolitica
strains in Southwest Finland from 2018 to 2022. Results show that the number of travel‐associated
S. enterica
and Campylobacter spp. declined markedly from autumn 2019 to autumn 2020 and have recovered gradually. Antimicrobial susceptibility testing was performed on bacterial strains isolated from PCR‐positive fecal specimens. Resistance patterns fluctuated throughout the study period. Among
C. jejuni
, ciprofloxacin resistance averaged 58% in domestic (n = 155) and 88% travel‐associated (n = 10) strains, while tetracycline resistance averaged 36% and 63%, respectively; erythromycin resistance was not detected. In
S. enterica
, resistance averaged 42% and 33% to ampicillin, 33% and 45% to fluoroquinolones, 4% and 6% to cefotaxime, and 0% and 2% to co‐trimoxazole, in domestic (n = 24) and travel‐associated (n = 32) strains, respectively. Among domestic
Y. enterocolitica
strains (n = 64), resistance averaged 7% to co‐trimoxazole, 2% to ciprofloxacin, and 1% to cefotaxime; no travel‐associated strains were reported. This study shows that lockdowns due to the COVID‐19 pandemic decreased the number of diagnosed enteropathogens and limited the emergence of resistant strains. Thus, our results reaffirm that travel remains the primary source of
S. enterica
infections in Finland.