AUTHOR=Vogt Nadine A. , Hetman Benjamin M. , Vogt Adam A. , Pearl David L. , Reid-Smith Richard J. , Parmley E. Jane , Kadykalo Stefanie , Janecko Nicol , Bharat Amrita , Mulvey Michael R. , Ziebell Kim , Robertson James , Nash John , Allen Vanessa , Majury Anna , Ricker Nicole , Bondo Kristin J. , Allen Samantha E. , Jardine Claire M. 

TITLE=Rural Raccoons (Procyon lotor) Not Likely to Be a Major Driver of Antimicrobial Resistant Human Salmonella Cases in Southern Ontario, Canada: A One Health Epidemiological Assessment Using Whole-Genome Sequence Data

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.840416

DOI=10.3389/fvets.2022.840416

ISSN=2297-1769

ABSTRACT=<p>Non-typhoidal <italic>Salmonella</italic> infections represent a substantial burden of illness in humans, and the increasing prevalence of antimicrobial resistance among these infections is a growing concern. Using a combination of <italic>Salmonella</italic> isolate short-read whole-genome sequence data from select human cases, raccoons, livestock and environmental sources, and an epidemiological framework, our objective was to determine if there was evidence for potential transmission of <italic>Salmonella</italic> and associated antimicrobial resistance determinants between these different sources in the Grand River watershed in Ontario, Canada. Logistic regression models were used to assess the potential associations between source type and the presence of select resistance genes and plasmid incompatibility types. A total of 608 isolates were obtained from the following sources: humans (<italic>n</italic> = 58), raccoons (<italic>n</italic> = 92), livestock (<italic>n</italic> = 329), and environmental samples (<italic>n</italic> = 129). Resistance genes of public health importance, including <italic>bla</italic><sub>CMY−2</sub>, were identified in humans, livestock, and environmental sources, but not in raccoons. Most resistance genes analyzed were significantly more likely to be identified in livestock and/or human isolates than in raccoon isolates. Based on a 3,002-loci core genome multi-locus sequence typing (cgMLST) scheme, human <italic>Salmonella</italic> isolates were often more similar to isolates from livestock and environmental sources, than with those from raccoons. Rare instances of serovars <italic>S</italic>. Heidelberg and <italic>S</italic>. Enteritidis in raccoons likely represent incidental infections and highlight possible acquisition and dissemination of predominantly poultry-associated <italic>Salmonella</italic> by raccoons within these ecosystems. Raccoon-predominant serovars were either not identified among human isolates (<italic>S</italic>. Agona, <italic>S</italic>. Thompson) or differed by more than 350 cgMLST loci (<italic>S</italic>. Newport). Collectively, our findings suggest that the rural population of raccoons on swine farms in the Grand River watershed are unlikely to be major contributors to antimicrobial resistant human <italic>Salmonella</italic> cases in this region.</p>