To determine the prevalence of antimicrobial-resistant bacteria among patients receiving care in high risk units in a Canadian tertiary care centre.
Prevalence study over a four-month period in 1995 with rectal swab or freshly passed stool specimen collected from each patient included in study. Standardized record data extraction for selected patient variables was used.
Units at high risk for antimicrobial-resistant organisms at the Health Sciences Centre, Winnipeg, including neonatal (NICU), pediatric (PICU), surgical (SICU) and medical intensive care units (MICU), central dialysis unit (CDU), and the in-patient oncology ward (ONC).
One hundred and fifty-seven patients admitted to the high risk care units for at least 72 h were screened. Ward distribution was NICU 13 (8.3%), PICU nine (5.7%), SICU 24 (15.3%), MICU 19 (12.1%), CDU 62 (39.5%) and ONC 30 (19.1%). Fifty-one of 157 (32.5%) patients had urinary drainage devices, 108 (68.8%) had invasive vascular devices, and 57 (36.3%) had had a surgical procedure within the month before specimen collection. In the month before sampling, 114 (72.6%) had received antimicrobial therapy, including 21 (13.3%) who had received vancomycin, and 81 (51.5%) were receiving antimicrobials, seven (10.8%) vancomycin, on the day of sampling.
Antimicrobial susceptibilities were performed on 371 bacterial isolates. There were no vancomycin-resistant enterococci or methicillin-resistant Staphylococcus aureus. Eleven (10.8%) enterococci were resistant to ampicillin, none of which were β-lactamase producers, 19 (18.6%) and five (4.9%) demonstrated high level resistance to gentamicin and streptomycin, respectively. One (0.7%) Escherichia coli was resistant to ciprofloxacin and another to gentamicin. Six (20.7%) Enterobacter cloacae samples were resistant to cefotaxime. One (2.4%) Klebsiella species was resistant to ciprofloxacin and another to cefotaxime. Two (16.6%) Citrobacter species were resistant to cefotaxime. One of 11 (9%) Pseudomonas aeruginosa isolates was resistant to ceftazidime; none were resistant to piperacillin, aminoglycosides, ciprofloxacin or imipenem.
The prevalence of antimicrobial-resistant organisms colonizing the gastrointestinal tract in patients in these high risk units is low. The reasons for this low prevalence of antimicrobial resistance require further exploration.