Prevalence and Antimicrobial Resistance of Dublin and Thermotolerant in Liver from Veal Calves in Québec, Canada.

Dublin and spp. are two foodborne pathogens of importance. A small number of studies reported that consumption of veal liver was associated with an increased risk of human illness from these two pathogens. To better characterize the risk of exposure from liver, a cross-sectional study was conducted to estimate the prevalence of white veal calf liver contamination with these two pathogens and to characterize the antimicrobial non-susceptibility patterns of isolates. Veal liver samples were collected at two slaughterhouses in Quebec, Canada, in 2016 and 2017. Samples were submitted for polymerase chain reaction (PCR) screening followed by culture of and thermotolerant . Isolates were tested for antimicrobial susceptibility using broth microdilution. Dublin was the only serotype cultured from 3.6% (95% confidence interval [CI]: 0.0-7.9) of 560 liver samples. Among them and for technical reasons, 498 were tested by PCR for . The prevalence of PCR-positive livers was estimated to be 65.8% (95% CI: 58.7-72.9) for and 7.0% (95% CI: 3.9-10.1%) for . Fourteen Dublin isolates were submitted for antimicrobial resistance (AMR) testing; all were non-susceptible to at least eight antimicrobials from six different classes. Most (81.4%) of the 188 isolates submitted for AMR testing were non-susceptible to tetracycline, and 23.0% of isolates were non-susceptible to nalidixic acid and ciprofloxacin. Of the seven isolates, four were multidrug resistant. This study highlights the importance of veal liver as a potential source of exposure to multidrug-resistant Dublin and thermotolerant spp.