Executive summary: 2008 Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) annual report

Executive Summary

The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) tracks temporal and regional trends in antimicrobial use and antimicrobial resistance in selected species of enteric bacteria obtained at different stages of food production and from human clinical laboratory submissions. This information supports the creation and evaluation of policies to contain antimicrobial resistance and to better manage antimicrobial use in human medicine, veterinary medicine, and agricultural sectors. CIPARS highlights antimicrobials considered to be of very high importance in human medicine (Category I of the antimicrobial classification system of the Veterinary Drugs Directorate, Health Canada), such as ceftriaxone and ciprofloxacin. CIPARS has now adopted the new resistance breakpoint of 4 µg/mL for ceftriaxone, resulting in an increase in reported ceftriaxone resistance that now closely parallels ceftiofur resistance.

Among the 3,601 human clinical isolates submitted for susceptibility testing in 2008, the 3 most commonly detected Salmonella serovars were Enteritidis, Typhimurium, and Heidelberg. Resistance to the Category I antimicrobial, ceftriaxone (and generally cross-resistance to ceftiofur and amoxicillin-clavulanic acid) among S. Heidelberg isolates (14%) remained higher than other serovars. The percentage of isolates with reduced susceptibility or resistance to ciprofloxacin ranged from 0% to 3%, with the exception of serovars Paratyphi A (89%), Typhi (72%), and Enteritidis (14%).

Reduced susceptibility or resistance to ciprofloxacin was not detected in any Salmonella isolates from abattoir or retail meat samples. However, reduced susceptibility to ciprofloxacin was detected in Escherichia coli recovered from samples of abattoir chickens, retail chicken, farm pigs, abattoir pigs, and retail pork (all ≤ 5%) but not in samples from abattoir beef cattle or retail beef. Full ciprofloxacin resistance was detected in less than 5% of Campylobacter isolates from abattoir beef cattle; Campylobacter, E. coli and Enterococcus isolates from retail chicken; E. coli isolates from retail pork; and Enterococcus isolates from farm pigs. In retail chicken from British Columbia and Saskatchewan, resistance to ciprofloxacin in Campylobacter was found in 8% and 10%, of isolates respectively.

The retail component of CIPARS is designed to examine inter-provincial differences in human exposure to antimicrobial resistance. For retail beef and pork, there were no significant differences among the provinces in percentages of isolates with antimicrobial resistance. However, for retail chicken, statistically significant ( P ≤ 0.05) differences across provinces/region were observed for resistance in E. coli, with higher percentages of isolates from British Columbia resistant to amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftiofur, and ceftriaxone than from Saskatchewan, Ontario, Québec, or the Maritimes region (except for ceftriaxone). The percentage of E. coli isolates from retail chicken with resistance to gentamicin was significantly higher for Québec than for British Columbia. Percentages of chicken E. coli isolates with resistance to sulfisoxazole and trimethoprim-sulfamethoxazole were significantly higher for Québec than for Saskatchewan.

Important temporal variations in antimicrobial resistance were also identified in retail chicken. The percentage of E. coli isolates from Saskatchewan with resistance to ceftiofur was significantly higher in 2008 than in 2007 or 2005 (first year of surveillance). Ceftiofur resistance was also higher in 2008 than in 2006 (last year of ceftiofur voluntary withdrawal) in chicken from Québec. The significant increase in retail chicken E. coli isolates from Québec with resistance to ceftiofur may have resulted from the resumption of extra-label ceftiofur use by broiler chicken hatcheries in 2007. A greater percentage of retail chicken E. coli isolates from Québec had resistance to nalidixic acid in 2008 than in 2003. The percentage of retail chicken Campylobacter from Ontario with resistance to azithromycin was also significantly higher in 2008 than in 2007. Vancomycin resistance was not detected in any Enterococcus isolates obtained from retail chicken and farm pigs.

With respect to human antimicrobial use, overall consumption in 2008 decreased, as measured by prescription dispensing rates and defined daily doses (DDDs)/1,000 inhabitant-days, to one of the lowest levels observed during the 9-year surveillance period. Category I antimicrobials continued to represent a high percentage (17%) of the total DDDs dispensed. There were provincial differences with respect to antimicrobial consumption, including differences in the consumption of fluoroquinolones, penicillins with extended spectrum, and macrolides, among others. When the total amount of oral antimicrobials dispensed in 2007 was compared with the total outpatient antimicrobial use in 19 European countries in the same year, Canada ranked 9th out of the 20 countries classified by increasing level of total antimicrobial consumption.

For antimicrobial use in animals, surveillance of sentinel swine herds (grower-finisher pigs) in 2008 revealed that the most commonly used antimicrobials belonged to Categories II or III (macrolides, lincosamides, penicillins, and tetracyclines). The only Category I antimicrobial used was ceftiofur, which was administered via injection to individual animals in 21% of the herds. At the herd level, an 8% decrease in ceftiofur use since 2007 was evident. Data from the Canadian Animal Health Institute regarding total kilograms of veterinary antimicrobials distributed for sale for all animals indicated a total of 1,615,571 kg was distributed in 2008. This represents a decrease of 9% relative to the total distributed in 2006 and a less than 1% decrease relative to the 2007 total. The quantity of fluoroquinolones distributed for use in animals in 2008 decreased by 30% relative to the 2006 total and by 7% relative to the 2007 total.

CIPARS is continually evolving to provide a better understanding of antimicrobial resistance in Canada, including discussions of farm surveillance of antimicrobial use and antimicrobial resistance in the broiler poultry sector. CIPARS also functions as a research platform, with involvement in projects studying aspects of use and resistance not covered by routine surveillance, such as additional populations (i.e. companion animals, sheep, wild small mammals, and subpopulations of people in Canada), additional regions (i.e. retail sampling in Alberta), and additional bacterial species of concern (i.e. methicillin-resistant Staphylococcus aureus and Clostridium difficile ). Short abstracts from selected research projects are presented in this report.