Brent P. Avery

Ceftiofur resistance in Salmonella enterica serovar Heidelberg from chicken meat and humans, Canada.

Use of this drug in chickens may limit effectiveness of cephalosporins in treating human infections.

Detection and Enumeration of Clostridium difficile Spores in Retail Beef and Pork

ABSTRACT Recent studies have identified Clostridium difficile in food animals and retail meat, and concern has been raised about the potential for food to act as a source of C. difficile infection in humans. Previous studies of retail meat have relied on enrichment culture alone, thereby preventing any assessment of the level of contamination in meat. This study evaluated the prevalence of C. difficile contamination of retail ground beef and ground pork in Canada. Ground beef and ground pork were purchased from retail outlets in four Canadian provinces. Quantitative and enrichment culture was performed. Clostridium difficile was isolated from 28/230 (12%) samples overall: 14/115 (12%) ground beef samples and 14/115 (12%) ground pork samples (P = 1.0). For ground beef, 10/14 samples (71%) were positive by enrichment culture only. Of the 4 ground beef samples that were positive by direct culture, 20 spores/g were present in 2 while 120 and 240 spores/g were present in 1 each. For ground pork, 10/14 (71%) samples were positive by enrichment culture only. Of the 4 ground pork samples that were positive by direct culture, 20 spores/g were present in 3 while 60 spores/g were present in 1. Ribotype 078 predominated, consistent with some previous studies of C. difficile in food animals. Ribotype 027/North American pulsotype 1 was also identified in both retail beef and pork. This study has identified relatively common contamination of retail ground beef and pork with C. difficile spores; however, the levels of contamination were very low.

Possible seasonality of Clostridium difficile in retail meat, Canada.

We previously reported Clostridium difficile in 20% of retail meat in Canada, which raised concerns about potential foodborne transmissibility. Here, we studied the genetic diversity of C. difficile in retail meats, using a broad Canadian sampling infrastructure and 3 culture methods. We found 6.1% prevalence and indications of possible seasonality (highest prevalence in winter).

Detection and characterization of Clostridium difficile in retail chicken.

Aims:  This study was designed to evaluate the prevalence of Clostridium difficile contamination of retail chicken.

Phenotypic and genetic characterization of antimicrobial resistance in Salmonella serovars isolated from retail meats in Alberta, Canada

This study determined the prevalence of Salmonella serovars, antimicrobial resistance (AMR) and resistance genes in Salmonella isolated from retail meats purchased in Alberta, Canada. Samples were collected during one year period (May 2007-April 2008) on weekly basis from 19 census divisions in Alberta. A total of 564 samples including chicken (n = 206), turkey (n = 91), beef (n = 134) and pork (n = 133) were purchased. Salmonella were recovered from chicken (40%), turkey (27%) and pork (2%) samples and was not found in ground beef. A total of 21, 8, and 3 different serovars were recovered from chicken, turkey and pork meats, respectively. Salmonella Hadar was most common in chicken whereas S. Heidelberg was common in turkey meat. Overall 29% (32/110) of isolates were susceptible to tested antimicrobials and resistance to ciprofloxacin, amikacin and nalidixic acid was not found in any isolate. Multiresistance (≥2 antimicrobials) was found in 56% of isolates. Resistance to amoxicillin-clavulanic acid (AMC), ceftiofur (TIO), and ceftriaxone (CRO) was found in about 21% of chicken and 25% of turkey isolates. Resistance to either of tetracycline (TET), streptomycin (STR) or ampicillin (AMP) was unconditionally associated with S. Hadar but resistance to either of TET, AMP, AMC, TIO, CRO or cefoxitin was associated with S. Heidelberg. The strA/B (42% isolates), tet(A) (28% isolates), bla(CMY-2) (21% isolates) and bla(TEM) (17% isolates) were the most common resistance genes found. The bla(CMY-2) and bla(TEM) genes were unconditionally associated with S. Heidelberg; tet(A) and strA/B with S. Hadar and tet(B) gene with S. Kentucky. The strA/B genes were not associated with S. Heidelberg. Our data suggests that the prevalence of Salmonella serovars varied by the meat type and that AMR and resistance genes varied by the Salmonella serovars.

Antimicrobial Resistance and Resistance Genes in Escherichia coli Isolated from Retail Meat Purchased in Alberta, Canada

This study analyzed antimicrobial resistance (AMR) and resistance genes in generic Escherichia coli isolated from retail meat samples purchased (2007-2008) in Alberta, Canada, and determined potential associations between resistance phenotypes and resistance genes with relation to the meat types. A total of 422 E. coli isolates from retail chicken, turkey, beef, and pork meats were tested for antimicrobial susceptibility. Multiplex PCRs were used to detect major resistance genes for tetracyclines [tet(A), tet(B), tet(C)], sulfonamides (sul1, sul2, sul3), aminoglycosides (strA/B, aadA, aadB, aac(3)IV, aphA1, aphA2), and β-lactamase (bla(CMY-2), bla(TEM), bla(SHV), bla(PSE-1)). Resistance to ciprofloxacin was not found in any isolate. Overall resistances to clinically important antimicrobials amoxicillin-clavulanic acid (16.8% of isolates) and ceftriaxone (12.6% isolates) were observed. These resistances were observed more frequently (p<0.0001) in chicken-derived E. coli than those from the other meat types. Resistance to multiple antimicrobials (≥ 5) was found in more chicken derived E. coli (32%) than E. coli from other meat types. The β-lactamase genes of clinical importance, including bla(CMY-2) and bla(TEM), were found in about 18% of poultry-derived E. coli and in only 5% of ground beef. The bla(CMY-2) gene was more likely to be found in E. coli from chicken than turkey, beef, or pork meats. The tet(A) gene was associated with bla(CMY-2), whereas bla(CMY-2) and bla(TEM) genes were associated with strA/B genes. Resistance genes for tetracycline, sulfonamides, and aminoglycosides were associated with the phenotypic expression of resistance to unrelated classes of antimicrobials. These data suggest the prevalence of AMR and select resistance genes were higher in poultry-derived E. coli. The multiple associations found between AMR phenotypes and resistance genes suggest a complex nature of resistance in E. coli from retail meat, and hence the use of a single antimicrobial could result in the selection of resistant E. coli not only to the drug being used but to other unrelated classes of antimicrobials as well.

Prevalence of Zoonotic Bacteria in Wild and Farmed Aquatic Species and Seafood: A Scoping Study, Systematic Review, and Meta-analysis of Published Research

Increased reliance on seafood has brought to light concerns regarding food safety, but the information to inform risk assessment or surveillance needs is lacking. A scoping study (ScS) was conducted to characterize published research investigating selected zoonotic bacteria and public health topics in various wild and farmed aquatic species and seafood. This was followed by a systematic review (SR) on selected bacteria (Aeromonas spp., generic Escherichia coli, Salmonella spp., and Vibrio spp.) and aquatic species (clams, mussels, oysters, salmon, and shrimp [including prawn]); a meta-analysis (MA) was conducted only at the retail level due to considerable variability among various pathogen/seafood combinations. The ScS revealed the most frequently investigated themes were farm-level prevalence and intervention research for Vibrio spp. and Aeromonas spp. Antimicrobial use (AMU) and the association between AMU and antimicrobial resistance were rarely investigated. The SR indicated a consistent lack of reporting regarding study methodology and results, precluding the use of many studies in and full benefits of MA. MA of Aeromonas, E. coli, and Salmonella prevalence in retail salmon resulted in pooled estimates of 13% (6-27%), 2% (0.1-11%), and 1% (0-5%), respectively. When MA of pathogen/seafood combination resulted in statistically significant heterogeneity (p<0.1), median/range were reported at the region level. The results from our ScS, SR, and MA could be used for better design of future bacteriological surveys of seafood and as inputs for risk assessments or surveillance initiatives in this field.

Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) Farm Program: results from finisher pig surveillance.

In 2006, the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) Farm Program was implemented in sentinel grower‐finisher swine herds in Québec, Ontario, Manitoba, Saskatchewan and Alberta. Herds were visited 1–3 times annually. Faecal samples were collected from pens of close‐to‐market (CTM) weight (>80 kg) pigs and antimicrobial use (AMU) data were collected via questionnaires. Samples were cultured for generic Escherichia coli and Salmonella and tested for antimicrobial susceptibility. This paper describes the findings of this program between 2006 and 2008. Eighty‐nine, 115 and 96 herds participated in this program in 2006, 2007 and 2008 respectively. Over the 3 years, antimicrobial resistance (AMR) levels remained consistent. During this period, resistance to one or more antimicrobials was detected in 56–63% of the Salmonella spp. isolates and 84–86% of E. coli isolates. Resistance to five or more antimicrobials was detected in 13–23% of Salmonella and 12–13% of E. coli. Resistance to drugs classified as very important to human health (Category I) by the Veterinary Drug Directorate (VDD), Health Canada, was less than or equal to 1% in both organisms. AMU data were provided by 100 herds in 2007 and 95 herds in 2008. Nine herds in 2007 and five herds in 2008 reported no AMU. The most common route of antimicrobial administration (75–79% of herds) was via feed, predominantly macrolides/lincosamides (66–68% of herds). In both 2007 and 2008, the primary reasons given for macrolide/lincosamide use were disease prevention, growth promotion and treatment of enteric disease. The Category I antimicrobials, ceftiofur and virginiamycin were not used in feed or water in any herds in 2008, but virginiamycin was used in feed in two herds in 2007. Parenteral ceftiofur was used in 29 herds (29%) in 2007 and 20 herds (21%) in 2008. The reasons for ceftiofur use included treatment of lameness, respiratory disease and enteric disease.

Ciprofloxacin-Resistant Campylobacter spp. in Retail Chicken, Western Canada

During 2005–2010, the Canadian Integrated Program for Antimicrobial Resistance Surveillance identified increased prevalence of ciprofloxacin (a fluororquinolone) resistance among Campylobacter isolates from retail chicken in British Columbia (4%–17%) and Saskatchewan (6%–11%), Canada. Fluoroquinolones are critically important to human medicine and are not labeled for use in poultry in Canada.

A Canadian Application of One Health: Integration of Salmonella Data from Various Canadian Surveillance Programs (2005–2010)

Most bacterial pathogens associated with human enteric illness have zoonotic origins and can be transmitted directly from animals to people or indirectly through food and water. This multitude of potential exposure routes and sources makes the epidemiology of these infectious agents complex. To better understand these illnesses and identify solutions to reduce human disease, an integrative approach like One Health is needed. This article considers the issue of Salmonella in Canada and interprets data collected by several Canadian surveillance and research programs. We describe recovery of Salmonella from various samples collected along the exposure pathway and compare the serovars detected in the different components under surveillance (animal, food, environment, and human). We then present three examples to illustrate how an approach that interprets multiple sources of surveillance data together is able to address issues that transcend multiple departments and jurisdictions. First, differences observed in recovery of Salmonella from different cuts of fresh chicken collected by different programs emphasize the importance of considering the surveillance objectives and how they may influence the information that is generated. Second, the high number of Salmonella Enteritidis cases in Canada is used to illustrate the importance of ongoing, concurrent surveillance of human cases and exposure sources to information domestic control and prevention strategies. Finally, changing patterns in the occurrence of ceftiofur-resistant Salmonella Heidelberg in retail meats and humans demonstrates how integrated surveillance can identify an issue in an exposure source and link it to a trend in human disease. Taken together, surveillance models that encompass different scales can leverage infrastructure, costs, and benefits and generate a multidimensional picture that can better inform disease prevention and control programs.