Antimicrobial resistance and recovery of , and from chicken egg layer flocks in Canadian sentinel surveillance sites using 2 types of sample matrices.

Eggs are important to the diet of Canadians. This product is one of the supply-managed commodities in Canada, but unlike other commodities, where food safety risks are extensively explored and reported, information on the prevalence of enteric organisms (e.g., ) and antimicrobial resistance (AMR) in layers in Canada are limited. This study was conducted to determine the prevalence of select bacteria and the associated AMR patterns in layer flocks using 2 sample matrices. Farms were located within FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance sentinel sites (SS). Fecal samples (Ontario: ON, ON) and environmental sponge swabs (British Columbia: BC) were collected. prevalence was 29% and 8% in ON and ON, respectively, and 7% in BC. . Kentucky and . Livingstone were the most frequently isolated serovars and no . Enteritidis was detected. was not detected in the BC sponge swabs but was isolated from 89% and 53% of Ontario fecal samples (ON and ON, respectively). Seven from Ontario were ciprofloxacin-resistant. prevalence was high in both sample types (98%). Overall, tetracycline resistance among ranged from 26% to 69%. Resistance to ceftiofur ( = 2 isolates) and gentamicin ( = 2) was relatively low. There were diverse resistance patterns (excludes susceptible isolates) observed among in Ontario (10 patterns) and British Columbia (14 patterns). This study revealed that fecal samples are more informative for farm-level monitoring of pathogen and AMR prevalence. Without further validation, sponge swabs are limited in their utility for detection and thus, for public health surveillance.