Antimicrobial susceptibility of 22746 pathogens from Canadian hospitals: results of the CANWARD 2007-11 study

The purpose of the CANWARD study was to assess the antimicrobial activity of a variety of available agents against 22746 pathogens isolated from patients in Canadian hospitals between 2007 and 2011. Between 2007 and 2011, 27123 pathogens were collected from tertiary-care centres from across Canada; 22746 underwent antimicrobial susceptibility testing using CLSI broth microdilution methods. Patient demographic data were also collected. Of the isolates collected, 45.2, 29.6, 14.8 and 10.4 were from blood, respiratory, urine and wound specimens, respectively. Patient demographics were as follows: 54.4/45.6 male/female, 12.8 17 years old, 45.1 1864 years old and 42.1 65 years old. Isolates were obtained from patients in medical and surgical wards (37.8), emergency rooms (25.7), clinics (18.0) and intensive care units (18.5). The three most common pathogens were Escherichia coli (20.1), Staphylococcus aureus [methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA)] (20.0) and Pseudomonas aeruginosa (8.0), which together accounted for nearly half of the isolates obtained. Susceptibility rates (SRs) for E. coli were 100 meropenem, 99.9 tigecycline, 99.7 ertapenem, 97.7 piperacillin/tazobactam, 93.7 ceftriaxone, 90.5 gentamicin, 77.9 ciprofloxacin and 73.4 trimethoprim/sulfamethoxazole. Twenty-three percent of the S. aureus were MRSA. SRs for MRSA were 100 daptomycin, 100 linezolid, 100 telavancin, 99.9 vancomycin, 99.8 tigecycline, 92.2 trimethoprim/sulfamethoxazole and 48.2 clindamycin. SRs for P. aeruginosa were 90.1 amikacin, 93.1 colistin, 84.0 piperacillin/tazobactam, 83.5 ceftazidime, 82.6 meropenem, 72.0 gentamicin and 71.9 ciprofloxacin. The CANWARD surveillance study has provided important data on the antimicrobial susceptibility of pathogens commonly causing infections in Canadian hospitals.