54 Methods
The methods and definitions used in this point-prevalence survey were similar to those described for the surveys con- ducted in 2010 and 2012.3,4 An invitation to participate was sent by email to all Canadian hospitals with at least 50 adult inpatients beds. Facilities providing only rehabilitation, psy- chiatric, pediatric, and long-term care were excluded. Partici- pating hospitals were asked to select 1 weekday between February 8 and February 19, 2016, to conduct the survey. On the day of the survey, all adult (≥18 years) inpatients in acute- care units were identified using the hospital census. Patients colonized or infected with MRSA, VRE, ESBL, or CRE, or who had CDI were flagged using infection prevention and control and laboratory databases were included (Appendix). A stan- dardized questionnaire was completed for each patient using the medical records to determine whether the patient met criteria for infection. Recorded information also included age, sex, date of admission, and anatomic site where the ARO was recovered. In addition, each participating site completed a standardized questionnaire describing hospital characteristics, infection pre- vention and control policies regarding AROs, and laboratory tests used to detect AROs. Infection control professionals at the participating hospitals attended standardized teleconference training for data collection. The Ethics Review Board at Sun- nybrook Health Sciences Centre in Toronto, Ontario, approved the study. Patients with MRSA, VRE, ESBL, or CRE were defined as
those who had a culture or molecular test confirming the presence of 1 of the AROs on the day of the survey or any time previously and who were on additional precautions (ie, contact precautions) for the organism. For this study, an ESBL producing organism was defined as an Enterobacteriacae resistant to at least 1 of the third-generation cephalosporins. A CRE was defined as an Enterobacteriacae resistant to at least 1 carbapenem antibiotic. Infection status was defined using the National Healthcare Safety Network criteria.5 CDI was defined by the presence of diarrhea (3 or more watery stools within 24 hours) with a positive C. difficile test (toxin assay or NAAT) and receipt of targeted treatment for this infection, or if pseudomembranous colitis had been docu- mented by endoscopy within the previous 14 days.3,4
Data analysis and statistical methods
The primary outcomes were the prevalence of MRSA, VRE, CDI, ESBL and CRE, calculated as the number of cases per 100 adult inpatients with 95% confidence interval (95% CI) in each of the participating hospitals on the date of the point-prevalence survey. For each ARO, median prevalences in 2012 and 2016 were compared by the Mann-Whitney U test. A χ2 test was used to compare selected ARO infection prevention and control hospital policies across the 3 years. Univariate and multivariate logistic regressions were conducted to identify hospital char- acteristics associated with prevalence of each ARO. Covariates significantly associated with the prevalence in univariate com- parisons were assessed for multicollinearity using tolerance statistics, and those with tolerance ≥0.4 were retained in the model. Poisson modeling for binomial distribution was con- ducted as sensitivity analyses and did not show major differ- ences with the logistic regression. All analyses were performed using SAS version 9.4 software (SAS Institute, Cary, North Carolina).
Results
In total, 160 hospitals participated in the survey, representing 36,524 adult acute-care beds in 9 of 10 provinces with a 96% occupancy rate (n=35,018) on the day of the survey. Char- acteristics of participating hospitals are shown in Table 1. Colonized or infected MRSA patients were reported from 152
(95%) of participating hospitals; patients with VRE were reported from 101 hospitals (63%); patients with ESBL were reported from 85 hospitals (53%); patients with CRE were reported from 24 hospitals (15%); and patients with CDI were reported from 123 hospitals (77%). Hospitals reported a total of 3,117 patients colonized or infected with at least 1 ARO, representing a pre- valence of 8.9 per 100 inpatients (95% CI, 7.9–9.9). Overall, 1,705 patients were colonized or infected with MRSA (4.9 per 100 inpatients; 95% CI, 4.3–5.4); 238 patients were infected with MRSA (0.7 per 100 inpatients; 95% CI, 0.5–0.8); 902 patients were colonized or infected with VRE (2.6 per 100 inpatients; 95% CI, 1.8–3.4); 24 patients were infected with VRE (0.07 per 100 inpatients; 95% CI, 0.04–0.10); 428 patients were colonized or infected with an ESBL-producing Enterobacteriaceae (1.2 per 100 inpatients; 95% CI, 1.0–1.6); 30 patients were colonized or infected with a CRE (0.09 per 100 inpatients; 95% CI, 0.05–0.12); and 436 patients had a confirmed CDI (1.2 per 100 inpatients; 95% CI, 1.1–1.4). Klebesiella spp were the most frequent genus with carbapenem
resistance, with 11 reported cases (34%) followed by Escherichia coli (28%) and Enterobacter spp (22%). Of the 31 reported CREs, 21 were characterized by a molecular test. NDM-1 was the most frequent carbapenemase enzyme in 8 cases (38%), followed by OXA-48 in 5 cases (24%) and by KPC in 4 cases (19%). Carriage sites are shown in Appendix Table 1. Significant differences in the geographical distribution of
AROs were observed (Fig. 1). The median prevalence of MRSA was higher in western Canada than in the rest of the country (P=.003). Western Canada also had the highest median pre- valence for VRE (P=.001). However, central Canada had a higher median prevalence of CDI (P=.001).
Table 1. Characteristics of Participating Hospitals in 2010, 2012, and 2016 Hospital Characteristic 2010, No. (%) 2012, No. (%) 2016, No. (%) Regiona Eastern Canada Central Canada Western Canada
26 (15) 103 (58) 47 (27)
Size ≤200 beds
201–500 beds >500 beds Type
Teaching Nonteaching
92 (52) 74 (42) 10 (6)
55 (31) 121 (69)
24 (17) 88 (61) 31 (22)
79 (55) 58 (41) 6 (4)
45 (31) 98 (69)
26 (16) 82 (51) 52 (33)
82 (51) 72 (45) 6 (4)
70 (44) 90 (56)
aEastern Canada: Newfoundland and Labrador, Prince Edward Island, Nova Scotia, and New Brunswick. Central Canada: Quebec and Ontario. Western Canada: Manitoba, Saskatchewan, Alberta, British Columbia, and the Northwest Territories.
Philippe Martin et al
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