Comparison of antimicrobial resistance among Salmonella enterica serovars isolated from Canadian turkey flocks, 2013 to 2021

The emergence of antimicrobial resis-tance (AMR) in Salmonella from turkeys has raised a food safety concern in Canada as certain serovars have been implicated in human salmonellosis outbreaks in recent years. While several studies evaluated AMR in broiler chickens in Canada, there are limited studies that assess AMR in turkey flocks. This study analyzed data collected between 2013 and 2021 by the Canadian Integrated Program for Antimicrobial Resistance Sur-veillance (CIPARS) farm turkey surveillance program to determine the prevalence of AMR and differences in resistance patterns among Salmonella serovars recov-ered from turkey flocks. Salmonella isolates were tested for susceptibility to 14 antimicrobials using a microbroth dilution method. Hierarchical clustering dendrograms were constructed to compare the individual AMR status of Salmonella serovars. Differences in the probability of resistance between Salmonella serovars were determined using generalized estimating equation logistic regression models to account for farm-level clustering. Of the 1,367 Salmonella isolates detected, 55.3% were resistant to at least one antimicrobial and 25.3% were multidrug resistant (MDR) (resistant to >= 3 antimicrobial classes). The Salmonella isolates exhibited high resistance to tet-racycline (43.3%), streptomycin (47.2%), and sulfisoxa-zole (29.1%). The 3 most frequently occurring serovars were S. Uganda (22.9%), S. Hadar (13.5%), and S. Read-ing (12.0%). Streptomycin-sulfisoxazole-tetracycline (n = 204) was the most frequent MDR pattern identi-fied. Heatmaps showed that S. Reading exhibited core-sistance to the quinolone class antimicrobials, ciprofloxacin, and nalidixic acid; S. Heidelberg to genta-micin and sulfisoxazole; and S. Agona to ampicillin and ceftriaxone. Salmonella Hadar isolates had higher odds of resistance to tetracycline (OR: 152.1, 95% CI: 70.6 -327.4) while the probability of being resistant to genta-micin and ampicillin was significantly higher in S. Senf-tenberg than in all the other serovars. Moreover, S. Uganda had the highest odds of being MDR (OR: 4.7, 95% CI: 3.7-6.1). The high resistance observed war-rants a reassessment of the drivers for AMR, including AMU strategies and other production factors. Differen-ces in AMR patterns highlight the need to implement

Automated summary

The study analyzed data from 2013 to 2021 collected by the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) farm turkey surveillance program. The results showed that Salmonella isolates from turkeys in Canada exhibited high resistance to multiple antibiotics. The study highlights the need to reassess antibiotic use strategies and other production factors.