Gram-negative pathogens from Canadian hospitals: 17 years of results from the CANWARD study (2007–23)

Abstract Objectives CANWARD is a Canadian Antimicrobial Resistance Alliance (CARA)/Health Canada partnered national surveillance study established in 2007 to annually assess the in vitro activities of commonly tested and recently approved antimicrobial agents for bacterial pathogens isolated from patients receiving care in Canadian hospitals. Methods In total, 34 155 Gram-negative pathogens were tested using the CLSI reference broth microdilution method. Results In total, 39.4%, 37.1%, 17.7% and 5.8% of isolates tested were from respiratory, blood, urine and wound specimens, respectively; 31.1%, 23.9%, 19.0%, 18.5% and 7.5% of isolates were from patients in medical wards, emergency rooms, ICUs, hospital clinics and surgical wards. In total, 51.8% of isolates were from male patients; and 10.1%, 40.7% and 49.2% of isolates were from patients aged ≤17, 18–64 and ≥65 years. The most common Gram-negative pathogens received were: Escherichia coli (34.9%), Pseudomonas aeruginosa (17.5%) and Klebsiella pneumoniae (11.6%). An ESBL-producing phenotype was identified in 8.4% of E. coli and 5.6% of K. pneumoniae isolates. Percent susceptible values for E. coli included: 100% for meropenem/vaborbactam and imipenem/relebactam; >99% for ceftazidime/avibactam, meropenem and ceftolozane/tazobactam; 95.6% for piperacillin/tazobactam; and 73.9% for ciprofloxacin. Percent susceptible values for K. pneumoniae included: >99% for meropenem/vaborbactam, imipenem/relebactam, ceftazidime/avibactam and meropenem; 97.4% for ceftolozane/tazobactam; 91.9% for piperacillin/tazobactam; and 87.0% for ciprofloxacin. Percent susceptible values for P. aeruginosa included: 96.6% for ceftolozane/tazobactam; 92.6% for ceftazidime/avibactam; 92.0% for imipenem/relebactam; 79.9% for piperacillin/tazobactam; ceftazidime 78.1%; 78.0% for meropenem; and 68.6% for ciprofloxacin. Conclusions The CANWARD surveillance study has provided 17 years of reference antimicrobial susceptibility testing data.