Coccidiosis is a self-limiting disease that is universally present in poultry operations, causing extensive damage to the intestinal lining of the bird. Global economic losses from coccidiosis are estimated to be $3 billion per year. In-feed anticoccidial use has been the predominant form of coccidiosis control. However, due to widespread emergence of antimicrobial resistance, concerns have been raised regarding the safety of anticoccidials and the potential impact on human, animal, and environmental health. To investigate the benefits, risks, and alternatives to anticoccidial use, a comprehensive review of recent literature was conducted. Several live vaccines are available, which, when used in combination with anticoccidials, have been shown to help restore sensitivity of infective parasites. However, their use has been limited because of increased cost; increased susceptibility to bacterial enteritis; challenges with consistent application; and slow development of immunity. Various alternative feed products are available, but do not have a direct anticoccidial effect, and few studies have demonstrated consistent field efficacy of these products. Consumer and environmental safety of anticoccidials is monitored and assessed by governing bodies. Furthermore, there is a lack of current evidence to indicate that bacterial resistance poses a public health concern. The findings from this review indicate that in the absence of alternatives, poultry production is optimized by using anticoccidials, benefiting all three pillars of sustainability, including social (bird health, welfare, and food safety), economic (production efficiency), and environmental aspects.

We have previously described the importance of using multiple indicators for reporting national farm-level antimicrobial use (AMU) information, but the distribution of flock-level AMU and how these indicators relate to each other has not yet been fully explored. Using farm-level surveillance data (2013-2019), for broiler chickens (n = 947 flocks) and turkeys (n = 427), this study aims to (1) characterize flock-level AMU and identify high users, (2) identify appropriate AMU indicators and biomass denominator [population correction unit (PCU) vs. kg weight at pre-slaughter], and (3) make recommendations on the application to veterinarian-producer and national-level reporting. Diverse AMU patterns were identified in broiler chickens (156 patterns) and turkeys (68 patterns); of these, bacitracin, reported by 25% of broiler chicken and 19% of turkey producers, was the most frequently occurring pattern. Depending on the indicator chosen, variations in reported quantity of use, temporal trends and relative ranking of the antimicrobials changed. Quantitative AMU analysis yielded the following results for broiler chickens: mean 134 mg/PCU; 507 number (n) of Canadian (CA) defined daily doses (DDDvet) per 1,000 chicken-days and 18 nDDDvetCA/PCU. Analysis in turkey flocks yielded the following: mean 64 mg/PCU, 99 nDDDvetCA/1,000 turkey-days at risk and 9 nDDDvetCA/PCU. Flocks were categorized based on the percentiles of the mg/PCU distribution: "medium" to "low" users (≤75th percentile) and "high" users (>75th percentile). The odds of being a high user in both broiler chickens and turkeys were significantly increased: if water medications were used, and if trimethoprim-sulfonamides, bacitracins, and tetracyclines were used. Pairwise correlation analysis showed moderate correlation between mg/PCU and the nDDDvetCA/1,000 animal days at risk and between mg/PCU and nDDDvetCA/PCU. Significantly high correlation between nDDDvetCA/1,000 animal days at risk and nDDDvetCA/PCU was observed, suggestive that either of these could be used for routine monitoring of trends in AMU. One source of discrepancy between the indicators was the antimicrobial. Understanding the Agunos et al. Flock-Level Distribution of AMU in Canadian Broiler Chickens and Turkeys choice of parameter input and effects on reporting trends in AMU will inform surveillance reporting best practices to help industry understand the impacts of their AMU reduction strategies and to best communicate the information to veterinarians, their producers, and other stakeholders.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi‐weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005–2013) and generic Escherichia coli (2012–2013). Of all samples tested, 16% of Salmonella and 22% of E. coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E. coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E. coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.

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Non-typhoidal Salmonella 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 Salmonella 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 Salmonella 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 (n = 58), raccoons (n = 92), livestock (n = 329), and environmental samples (n = 129). Resistance genes of public health importance, including blaCMY−2, 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 Salmonella isolates were often more similar to isolates from livestock and environmental sources, than with those from raccoons. Rare instances of serovars S. Heidelberg and S. Enteritidis in raccoons likely represent incidental infections and highlight possible acquisition and dissemination of predominantly poultry-associated Salmonella by raccoons within these ecosystems. Raccoon-predominant serovars were either not identified among human isolates (S. Agona, S. Thompson) or differed by more than 350 cgMLST loci (S. 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 Salmonella cases in this region.