Prior environmental contamination increases the risk of acquisition of vancomycin-resistant enterococci.
BACKGROUND
Patients colonized with vancomycin-resistant enterococci (VRE) frequently contaminate their environment, but the environmental role of VRE transmission remains controversial.


METHODS
During a 14-month study in 2 intensive care units, weekly environmental and twice-weekly patient surveillance cultures were obtained. VRE acquisition was defined as a positive culture result >48 h after admission. To determine risk factors for VRE acquisition, Cox proportional hazards models using time-dependent covariates for colonization pressure and antibiotic exposure were examined.


RESULTS
Of 1330 intensive care unit admissions, 638 patients were at risk for acquisition, and 50 patients (8%) acquired VRE. Factors associated with VRE acquisition included average colonization pressure (hazard ratio [HR], 1.4 per 10% increase; 95% confidence interval [CI], 1.2-1.8), mean number of antibiotics (HR, 1.7 per additional antibiotic; 95% CI, 1.2-2.5), leukemia (HR, 3.1; 95% CI, 1.2-7.8), a VRE-colonized prior room occupant (HR, 3.1; 95% CI, 1.6-5.8), any VRE-colonized room occupants within the previous 2 weeks (HR, 2.5; 95% CI, 1.3-4.8), and previous positive room culture results (HR, 3.4; 95% CI, 1.2-9.6). In separate multivariable analyses, a VRE-colonized prior room occupant (HR, 3.8; 95% CI, 2.0-7.4), any VRE-colonized room occupants within the previous 2 weeks (HR, 2.7; 95% CI, 1.4-5.3), and previous positive room culture results (HR, 4.4; 95% CI, 1.5-12.8) remained independent predictors of VRE acquisition, adjusted for colonization pressure and antibiotic exposure.


CONCLUSIONS
We found that prior room contamination, whether measured via environmental cultures or prior room occupancy by VRE-colonized patients, was highly predictive of VRE acquisition. Increased attention to environmental disinfection is warranted.
Drees
Marci
M
Tufts-New England Medical Center, Boston Massachusetts, USA. mdrees@christianacare.org
Snydman
David R
DR
Schmid
Christopher H
CH
Barefoot
Laurie
L
Hansjosten
Karen
K
Vue
Padade M
PM
Cronin
Michael
M
Nasraway
Stanley A
SA
Golan
Yoav
Y
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission*; D016983:Enterococcus / Q000187:drug effects* / Q000302:isolation & purification; D004783:Environmental Microbiology; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents