Ciprofloxacin is important for treatment of severe or invasive Salmonella infections in humans. As laboratories transition from phenotypic to genomics-based methods for determining ciprofloxacin non-susceptibility, it is important to define the correlation between genetic determinants of resistance and phenotypic outcomes. Here, we examined ciprofloxacin resistance mechanisms in Salmonella and tested the hypothesis that isolates containing only one mechanism had intermediate resistance while isolates containing two or more mechanisms had full resistance according to breakpoints from the Clinical Laboratory Standards Institute. Among 13,750 human and food/animal Salmonella enterica isolates, 2325 were predicted to be non-susceptible to ciprofloxacin using whole genome sequencing and Staramr. The most common mechanisms of resistance were mutations in gyrA (especially S83F and D87N/D87Y) and the qnrB19 allele. Only 28% of ciprofloxacin resistant isolates had two or more resistance mechanisms; the remainder contained only one mechanism. Of isolates with two or more mechanisms, only 63% were resistant. Thus, the number of genetic determinants of ciprofloxacin resistance in an isolate could not reliably differentiate the ciprofloxacin intermediate or resistant categories when using North American breakpoints. Predicting ciprofloxacin intermediate/resistant as a single non-susceptible category would facilitate global standardization of data to inform public health surveillance, treatment guidelines and stewardship.

Colistin is a last-resort treatment for highly drug-resistant bacterial infections. Of 47,184 Salmonella isolates collected from 2017 to 2022 in Canada from human and animal/food sources, mobile colistin resistance (mcr) variants conferring colistin resistance were detected exclusively in humans (n = 15). These variants were mcr-1.1 (n = 7), mcr-3.1 (n = 5), mcr-3.2 (n = 2), and mcr-1.2 (n = 1). The most common mcr-containing serotypes were I 4,[5],12:i:- (n = 8) and Typhimurium (n = 3). The proportion of Salmonella carrying mcr genes remains low in Canada (0.03%). IMPORTANCE:Colistin can be used in combination with other drugs as salvage therapy for extensively drug-resistant infections. If mobile colistin resistance (mcr) becomes widely disseminated in Enterobacterales, colistin will no longer be an option for salvage therapy in otherwise untreatable infections. While colistin is not commonly used to treat human Salmonella infections, Salmonella represents an important reservoir of mcr genes that may be transmitted to other gram-negative bacteria. Our aim was to determine the occurrence of mcr genes in Salmonella isolates collected from humans, food animals, and retail meats in Canada.

The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) monitors Escherichia coli, Salmonella and Campylobacter and their resistance to antimicrobials in broiler chickens at the farm and slaughter plant levels. In response to many years of CIPARS' observations and farmers' data, the Chicken Farmers of Canada implemented a strategy to reduce antimicrobial use in 2014. As resistance genes can be transmitted vertically from parents to their offspring, a study was conducted in broiler breeder flocks to assess the frequency of target bacteria, their antimicrobial resistance (AMR) and to obtain a comprehensive picture of AMR in poultry production. Spent breeder flocks slaughtered between 2018 and 2021 were sampled and data from broiler flocks at the farm and slaughter plants were assessed. Salmonella was most frequently detected in farm broiler chickens (46%), while Campylobacter was most frequently detected in broiler breeders (73%). In Campylobacter, high levels (20-24%) of ciprofloxacin resistance were found across the three production stages, and was highest in farm broiler chickens (24%). In E. coli, an indicator organism, low-level ceftriaxone resistance and occasional isolates that were non-susceptible to ciprofloxacin were noted. Using the indicator, fully susceptible E. coli, broiler breeders had the highest frequency (54%) compared to farm (36%) and slaughtered (35%) broiler chickens. In Salmonella broiler breeders had the highest resistance to most antimicrobials tested.Fully susceptible Salmonella was lowest in broiler breeders (16%) compared to farm (42%) and slaughtered (42%) broiler chickens. Salmonella serovars differed between the production stages, but S. Kentucky was the most predominant. Resistance to critically important antimicrobials in human medicine and regional variations in resistance profiles were observed. This study suggests that broiler breeders carry foodborne bacteria resistant to antimicrobials used in human medicine, demonstrating their role in the maintenance of AMR in poultry and the need to adopt a harmonized sector-wide AMU strategy.

To prevent the spread of foodborne illnesses, the presence of pathogens in the food chain is monitored by government agencies and food producers. The culture-based methods currently employed are sensitive but time- and labor-intensive, leading to increasing interest in exploring culture-independent diagnostic tests (CIDTs) for pathogen detection. However, few studies quantify the relative sensitivity and reliability of these CIDTs compared to current approaches. To address this issue, we conducted a comparison of the limit of detection (LOD50) for Salmonella between a culture-based method and three CIDTs: qPCR (targeting invA and stn), metabarcode (16S) sequencing, and shotgun metagenomic sequencing. Samples of chicken feed and chicken caecal contents were spiked with S. serovar Enteritidis and subjected to culture- and DNA-based detection methods. To explore the impact of non-selective enrichment on LOD50, all samples underwent both immediate DNA extraction and overnight enrichment prior to gDNA extraction. In addition to this spike-in experiment, feed and caecal samples acquired from the field were tested with culturing, qPCR, and metabarcoding. In general, LOD50 was comparable between qPCR and shotgun sequencing methods. Overnight microbiological enrichment resulted in an improvement in LOD50 with up to a three-log decrease. However, Salmonella reads were detected in some unspiked feed samples, suggesting false-positive detection of Salmonella. In addition, the LOD50 in feeds was three logs lower than in caecal contents, underscoring the impact of background microbiota on Salmonella detection using all methods. IMPORTANCE:The appeal of culture-independent diagnostic tests (CIDTs) is increased speed with lowered cost, as well as the potential to detect multiple pathogen species in a single analysis and to monitor other areas of concern such as antimicrobial resistance genes or virulence factors. This study provides quantitative data on the sensitivity of CIDTs relative to current approaches, which is essential for determining the feasibility of implementing these methods in pathogen surveillance programs.

The emergence of antimicrobial-resistant organisms at the human-animal-environment interface has raised global concern prompting governments and various stakeholders to take action. As a part of the stewardship initiative, Canadian turkey producers have implemented an antimicrobial use (AMU) strategy to manage antimicrobial resistance (AMR) in their sector. This study evaluated farm-level AMU and AMR data collected between 2016 and 2021 in major turkey-producing provinces/regions through the Canadian Integrated Program for Antimicrobial Resistance Surveillance to assess the progress of the strategy by characterizing the prevalence of homologous and multidrug resistance (MDR) in Escherichia coli isolated from turkeys. Multivariable mixed-effect logistic regression models assessed temporal and provincial/regional variations in AMR and MDR. Negative binomial regression models examined the temporal and regional variations in the total AMU. The total AMU (measured in mg/kg turkey biomass) significantly decreased in all provinces/regions in 2020 and 2021. Escherichia coli isolates from turkey flocks showed a significant decrease in resistance to gentamicin, sulfisoxazole, and tetracyclines during the six-year study period, consistent with the timing of the AMU reduction strategy. The prevalence of MDR isolates was significantly lower in 2020 and 2021 compared to 2016. Higher prevalence was observed in the Western region compared to Québec and Ontario. Two common AMR patterns were identified: ampicillin-streptomycin-tetracyclines and streptomycin-sulfisoxazole-tetracyclines. These AMR patterns indicate possible cross-resistances (same class), co-selection (unrelated classes) for resistance, or potential carryover of resistance determinants from previous production cycles. The decreasing prevalence of resistance to homologous antimicrobials, MDR, and AMU quantity are suggestive that the turkey sector's AMU strategy is achieving its desired impact. However, antimicrobials previously eliminated for preventive use in turkey flocks and the use of highly important antimicrobials in human medicine suggest that the AMU reduction strategy should be monitored and re-evaluated periodically to mitigate the emergence of MDR bacteria and safeguard animal and public health.

The study objective was to determine the occurrence and antimicrobial resistance (AMR) attributes of select foodborne bacteria recovered from egg -producing (layer) chickens between 2007 and 2021 using different sample matrices (Study 1: liquid whole eggs, Study 2: spent hen cecal samples, Study 3: environmental sponge swabs and fecal samples from layer chicken barns, and Study 4: fecal samples from layer chicken barns). Samples from each study were submitted for the culture of Escherichia coli and Salmonella. In addition, samples from layer chicken barns were submitted for the culture of Campylobacter. Isolates were tested by microbroth dilution and interpreted using both clinical breakpoints and epidemiological cut-offs (ECOFFs). The ECOFFs were applied to detect non -wild type (NWT) strains. The proportion of resistant, NWT, and distribution of minimum inhibitory concentrations (MIC) were assessed. Ceftriaxone resistance was detected at a low-level in E. coli (< 2 %, all studies) and Salmonella (4.3 %, Study 2). Very low-level ciprofloxacin resistance was detected in E. coli (<1 %, Study 1) but a slightly elevated ciprofloxacin NWT E. coli (1 % to 6 %) observed. Only the farm fecal samples in Studies 2 and 3 were tested for Campylobacter as part of its study design, and moderate level ciprofloxacin resistance (<15 %) was observed. The MIC distribution patterns were similar across the organisms tested/studies and no substantial shifts in the distributions were detected. This analysis demonstrated that resistance to very important antimicrobials in bacteria from layers in Canada remains low, however, the detection of ciprofloxacinresistant Campylobacter and the implications of this observation to the safety of egg products, and the role of laying flocks (i.e., as reservoir for resistant organisms) needs to be investigated.

We investigated whether the increased prevalence of gentamicin resistance in Salmonella from human infections was related to a similar increased prevalence in isolates from broiler chickens and whether this increase may have been due to coselection from use of lincomycin-spectinomycin in chickens on farms. Whole-genome sequencing was performed on gentamicin-resistant (Genr) Salmonella isolates from human and chicken sources collected from 2014 to 2017 by the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). We determined the genomic relatedness of strains and characterized resistance genes and plasmids. From 2014 to 2017, 247 isolates of Genr Salmonella were identified by CIPARS: 188 were from humans, and 59 were from chicken sources (26 from live animals on farm and 33 from retail meat). The five most common Genr serovars were Salmonella enterica serovars Heidelberg (n = 93; 31.5%), 4,[5],12:i:- (n = 42; 14.2%), Kentucky (n = 37; 12.5%), Infantis (n = 33; 11.2%), and Typhimurium (n = 23; 7.8%). Phylogenomic analysis revealed that for S. Heidelberg and S. Infantis, there were closely related isolates from human and chicken sources. In both sources, resistance to gentamicin and spectinomycin was most frequently conferred by aac(3)-VIa and ant(3'')-Ia, respectively. Plasmid closure confirmed linkages of gentamicin and spectinomycin resistance genes and revealed instances of similar plasmids from both sources. Gentamicin and spectinomycin resistance genes were linked on the same plasmids, and some plasmids and isolates from humans and chickens were genetically similar, suggesting that the use of lincomycin-spectinomycin in chickens may be selecting for gentamicin-resistant Salmonella in broiler chickens and that these resistant strains may be acquired by humans.

A group of experts from all Canadian federal food safety partners was formed to monitor the potential issues relating to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) food contamination, to gather and consider all of the relevant evidence and to determine the impact for Canadian food safety. A comprehensive risk pathway was generated to consider the likelihood of a SARS-CoV-2 contamination event at any of the relevant steps of the food processing and handling chain and the potential for exposure and transmission of the virus to the consumer. The scientific evidence was reviewed and assessed for each event in the pathway, taking into consideration relevant elements that could increase or mitigate the risk of contamination. The advantage of having an event-wise contextualization of the SARS-CoV-2 transmission pathway through the food chain is that it provides a systematic and consistent approach to evaluate any new data and communicate its importance and impact. The pathway also increases the objectivity and consistency of the assessment in a rapidly evolving and high-stakes situation. Based on our review and analysis, there is currently no comprehensive epidemiological evidence of confirmed cases of SARS-CoV-2, or its known variants, causing coronavirus disease 2019 from transmission through food or food packaging. Considering the remote possibility of exposure through food, the likelihood of exposure by ingestion or contact with mucosa is considered negligible to very low, and good hygiene practices during food preparation should continue to be followed.

Data on antimicrobial use (AMU) in pig production are needed for the development of good antimicrobial stewardship practices to reduce the risk of antimicrobial resistance in bacteria that can cause illness in animals and humans. In Canada, there is a lack of quantitative data on AMU in the farrowing and nursery stages of pig production. This study aimed to determine which antimicrobial active ingredients are currently used in farrowing, nursery, and grower-finisher herds in the province of Ontario, Canada, and to quantify AMU using various metrics. We collected data on herd demographics, biosecurity, health status, and AMU during one production cycle from 25 farrowing and 25 nursery herds in Ontario, between May 2017 and April 2018, and obtained data from 23 Ontario grower-finisher herds during the same time frame from the Public Health Agency’s Canadian Integrated Program for Antimicrobial Resistance Surveillance. We applied frequency measures, and weight-, and dose-based metrics to the data. In all pigs, the highest quantity of AMU was administered in-feed. By all routes of administration and compared to other production stages, nursery pigs used more antimicrobials in mg/kg biomass and the number of Canadian defined daily doses per 1000 pig-days (doseCA rate), while grower-finisher pigs used more antimicrobials in total kilograms and the number of Canadian defined daily doses per pig. In suckling pigs in some herds, there was routine disease prevention use of ceftiofur, an antimicrobial active ingredient categorized as very highly important in human medicine by Health Canada. The top antimicrobial used in each stage of pig production often varied by the metric used. There was producer-reported growth promotion use of antimicrobials in suckling and grower-finisher feed. The results of this study provide a current picture of AMU in pigs in Ontario and can be used as a basis for further research on AMU in farrowing and nursery herds in Canada. Our findings confirm that it would be useful to include farrowing and nursery herds in routine AMU surveillance in Canada. A future analysis using data from this project will examine factors that affect the quantity of AMU.

Extended-spectrum β-lactamases (ESBLs) confer resistance to extended-spectrum cephalosporins, a major class of clinical antimicrobial drugs. We used genomic analysis to investigate whether domestic food animals, retail meat, and pets were reservoirs of ESBL-producing Salmonella for human infection in Canada. Of 30,303 Salmonella isolates tested during 2012–2016, we detected 95 ESBL producers. ESBL serotypes and alleles were mostly different between humans (n = 54) and animals/meat (n = 41). Two exceptions were blaSHV-2 and blaCTX-M-1 IncI1 plasmids, which were found in both sources. A subclade of S. enterica serovar Heidelberg isolates carrying the same IncI1-blaSHV-2 plasmid differed by only 1–7 single nucleotide variants. The most common ESBL producer in humans was Salmonella Infantis carrying blaCTX-M-65, which has since emerged in poultry in other countries. There were few instances of similar isolates and plasmids, suggesting that domestic animals and retail meat might have been minor reservoirs of ESBL-producing Salmonella for human infection.

Antimicrobial resistance (AMR) in enteric bacteria continues to be detected in turkey flocks and retail products worldwide, including in Canada. However, studies assessing linkages between on-farm antimicrobial use (AMU) and the development of AMR are lacking. This study aims to identify AMU characteristics that impact the development of AMR in the indicator bacteria Escherichia coli in turkey flocks, building on the Canadian Integrated Program for Antimicrobial Resistance Surveillance methodology for farm-level AMU and AMR data integration. Two analytic approaches were used: (1) multivariable mixed-effects logistic regression models examined associations between AMU (any route, route-specific, and route-disease-specific indication) summarized as the number of defined daily doses in animals using Canadian standards ([nDDDvetCA]/1,000 kg-animal-days at risk) and AMR and (2) multivariable mixed-effects Poisson regression models studied the linkages between AMU and the number of classes to which an E. coli isolate was resistant (nCRE. coli). A total of 1,317 E. coli isolates from a network of 16 veterinarians and 334 turkey producers across the five major turkey-producing provinces in Canada between 2016 and 2019 were used. Analysis indicated that AMR emerged with the use of related antimicrobials (e.g., tetracycline use-tetracycline resistance), however, the use of unrelated antimicrobial classes was also impacting AMR (e.g., aminoglycosides/streptogramins use-tetracycline resistance). As for studying AMU-nCRE. coli linkages, the most robust association was between the parenteral aminoglycosides use and nCRE. coli, though in-feed uses of four unrelated classes (bacitracin, folate pathway inhibitors, streptogramins, and tetracyclines) appear to be important, indicating that ongoing uses of these classes may slow down the succession from multidrug-resistant to a more susceptible E. coli populations. The analysis of AMU (route and disease-specific)-AMR linkages complemented the above findings, suggesting that treatment of certain diseases (enteric, late-stage septicemic conditions, and colibacillosis) are influential in the development of resistance to certain antimicrobial classes. The highest variances were at the flock level indicating that stewardship actions should focus on flock-level infection prevention practices. This study added new insights to our understanding of AMU-AMR linkages in turkeys and is useful in informing AMU stewardship in the turkey sector. Enhanced surveillance using sequencing technologies are warranted to explain molecular-level determinants of AMR.

Surveillance of antimicrobial use (AMU) and antimicrobial resistance (AMR) is a core component of the 2017 Pan-Canadian Framework for Action. There are existing AMU and AMR surveillance systems in Canada, but some stakeholders are interested in developing their own AMU monitoring/surveillance systems. It was recognized that the establishment of core (minimum) AMU data elements, as is necessary for policy or intervention development, would inform the development of practical and sustainable AMU surveillance capacity across food animal sectors in Canada. The Canadian Animal Health Surveillance System (CAHSS) AMU Network was established as a multisectoral working group to explore the possibility of harmonizing data inputs and outputs. There was a consensus that a minimum AMU dataset for AMU surveillance (MDS-AMU-surv) should be developed to guide interested parties in initiating AMU data collection. This multisectoral collaboration is an example of how consultative consensus building across relevant sectors can contribute to the development of harmonized approaches to AMU data collection and reporting and ultimately improve AMU stewardship. The MDS-AMU-surv could be used as a starting point for the progressive development or strengthening of AMU surveillance programs, and the collaborative work could serve as a model for addressing AMR and other shared threats at the human–animal–environment interface.

The objective of this study was to evaluate preferences for various metrics and denominators among Canadian swine veterinarians, in order to improve reporting of antimicrobial use (AMU) information to these stakeholders and to facilitate enhanced stewardship decisions. An online survey was made available to swine veterinarians across Canada; 12 responses (estimated response rate 17.6%) were submitted and analyzed. Responses represented veterinarians from every major pig-producing province and from a range of year of graduation from veterinary college. Participants self-evaluated their understanding of dose-based metrics as higher than weight- and frequency-based metrics and interpreted most results of AMU analyses correctly. Participants preferred dose-based metrics over others, and had various objectives for AMU information, including improving AMU on their clients' farms and enabling comparisons with other farms. The results are useful to those making decisions about which AMU metrics to use in reports targeted to swine veterinarians.

This study explores methodologies for the data integration of antimicrobial use (AMU) and antimicrobial resistance (AMR) results within and across three food animal species, surveyed at the farm-level by the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). The approach builds upon existing CIPARS methodology and principles from other AMU and AMR surveillance systems. Species level data integration involved: (1) standard CIPARS descriptive and temporal analysis of AMU/AMR, (2) synthesis of results, (3) selection of AMU and AMR outcomes for integration, (4) selection of candidate AMU indicators to enable comparisons of AMU levels between species and simultaneous assessment of AMU and AMR trends, (5) exploration of analytic options for studying associations between AMU and AMR, and (6) interpretation and visualization. The multi-species integration was also completed using the above approach. In addition, summarized reporting of internationally-recognized indicators of AMR (i.e., AMR adjusted for animal biomass) and AMU (mg/population correction unit, mg/kg animal biomass) is explored. It is envisaged that this approach for species and multi-species AMU–AMR data integration will be applied to the annual CIPARS farm-level data and progressively developed over time to inform AMU–AMR integrated surveillance best practices for further enhancement of AMU stewardship actions.

Antimicrobial resistance surveillance targeting agricultural animals is practiced in many countries but does not often include media selective for cephalosporin resistance. Here, we compared the frequency of recovery of resistant Escherichia coli using selective and non-selective media from the cecal contents of 116 chickens collected by the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). Third generation cephalosporin resistance was detected in 24 samples including 12, 10, and 2 on selective, non-selective, and both media, respectively. Isolates producing the CTX-M-1 ESBL were grown from 11 samples, 10 on selective medium only. Our results suggest that current surveillance approaches underestimate the true prevalence of resistance to critically important antimicrobials.

Antimicrobial resistance (AMR) is a major public health threat worldwide. The main objective of this study was to compare AMR in Campylobacter from broiler chickens raised on Canadian farms and their products in different geographical regions of Canada. To do this, antimicrobial susceptibility results from isolates of Campylobacter recovered from a national microbiological baseline study conducted in federally registered establishments and in the retail marketplace were analyzed. Among 1460 isolates tested, 774 (53%) were resistant to at least one antimicrobial, with a predominance of three profiles: tetracycline (39%), quinolone-tetracycline (6.6%), and quinolones only (3.5%). The results showed no significant difference in the frequency of resistant profiles (p >= 0.05) among the isolates originating from different points in the food processing chain at slaughterhouses and in retail establishments. This suggests that AMR observed in Campylobacter isolates from raw chicken at retail originated further upstream in the system. A difference in the frequency of certain resistance profiles was observed between the regions of Canada. For instance, in British Columbia, there was more resistance to quinolones, while in Ontario and Quebec, Campylobacter isolates were more resistant to tetracyclines, macrolides, ketolides, and lincosamides. Comparison of AMR data from this study with those from the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) did not show any significant difference and provides evidence that CIPARS produces nationally representative resistance results.

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 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) is a global public health threat. The main purpose of this study was to evaluate AMR in generic Escherichia coli and Salmonella recovered from broiler chickens in Canada. To do this, an analysis of the antimicrobial susceptibility results was performed on a sample of generic E. coli and Salmonella isolates from the 2012 to 2013 national microbiological baseline study in broiler chicken. Of the 1135 generic E. coli isolates tested, 940 (82.8%) were resistant to at least one antimicrobial, with a large number of unique AMR profiles observed. Of the 1495 Salmonella isolates tested, 879 (58.8%) were resistant to at least one antimicrobial. Resistance was most common to aminoglycosides, β-lactams, and tetracyclines and, for generic E. coli isolates only, folate inhibitors. Differences in AMR patterns were observed across regions for both E. coli and Salmonella. For Salmonella, the levels of resistance were similar across the different sectors sampled along the food chain (e.g., slaughterhouse and retail) and the types of product sampled. There were also considerable differences in the levels and patterns of resistance among different Salmonella serovars, with most Salmonella Enteritidis isolates being susceptible to all antimicrobials tested.

Historically, extended-spectrum cephalosporin resistance in bacteria from animals in Canada has been attributed to the SHV and CMY β-lactamase families. This pattern is beginning to change with the emergence of the blaCTX-M gene family among Escherichia coli recovered from various animal species. Here we analyze and compare whole genome sequences of blaCTX-M-positive E. coli isolates (n = 173) from dogs, chicken, swine, horses and beef cattle in Canada. Ten blaCTX-M variants were identified with blaCTX-M-1,-14, -15, -27 and blaCTX-M-55 being identified in most animal species. These variants occurred across many sequence types, suggesting that mobile genetic elements mediate the spread of blaCTX-M. The variants blaCTX-M-14, -15, -27 and blaCTX-M-55 are associated with the global spread of blaCTX-M in human clinical isolates and their presence could be indicative of transfer between humans and animals. These variants were also the principal variants identified among sequence type 131 isolates, which were not associated with any other species than dogs. These isolates carried the same blaCTX-M variants as E. coli isolates found in humans. Close contact may promote the transmission of these isolates between humans and companion animals.

Using data from the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), we aimed to describe trends in antimicrobial use (AMU) in broiler chickens and turkeys, to compare AMU across species, to compare with trends in antimicrobial resistance (AMR), and to assess the effects of various AMU/AMR units of measurement (metrics and indicators) on data integration. Data on AMU and AMR in enteric bacteria, collected from 2013 to 2017 from broiler chickens (n = 143 flocks) and turkeys (n = 145) were used. In broiler chickens, the total AMU in milligrams/population correction unit (mg/PCUBr) decreased by 6%, the number (n) of defined daily doses for animals using Canadian standards (nDDDvetCA) per 1,000 broiler chicken-days decreased by 12%, and nDDDvetCA/PCU decreased by 6%. In turkeys, the mg/PCUTk decreased by 1%, whereas the nDDDvetCA/1,000 turkey-days and the nDDDvetCA/PCU increased by 1 and 5%, respectively. The types of antimicrobial classes used in both species were similar. Using the frequency of flocks reporting use (i.e., number of flocks reporting use/number of flocks participating) as a measurement, the use of certain antimicrobials changed over time (e.g., Broilers, decreased cephalosporin use, virginiamycin use, emerging use of lincomycin-spectinomycin, and avilamycin; Turkeys: increased trimethoprim-sulfonamides and macrolide use). The trends in resistance to specific antimicrobials paralleled the frequency and quantity of use (e.g., ceftriaxone use decreased-ceftriaxone resistance decreased, and gentamicin use increased-gentamicin resistance increased) in some situations, but not others (decreased fluoroquinolone use-increased ciprofloxacin resistance). AMR data were summarized using the AMR indicator index (AMR Ix). The most notable AMR Ix trend was the decrease in ceftriaxone AMR Ix among Escherichia coli (0.19 to 0.07); indicative of the success of the poultry industry action to eliminate the preventive use of third generation cephalosporins. Other trends observed were the increase in ciprofloxacin AMR Ix among Campylobacter from 0.23 to 0.41 and gentamicin AMR Ix among E. coli from 0.11 to 0.22, suggestive of the persistence/emergence of resistance related to previous and current AMU not captured in our surveillance timeframe. These data highlight the necessity of multiple AMU and AMR indicators for monitoring the impact of stewardship activities and interventions.