Vancomycin-resistant enterococci (VRE) outbreak at a university hospital in Kitakyushu, Japan: case-control studies

Abstract

At a university hospital in Japan, a total of 15 patients (14 adults and 1 newborn baby) with vancomycinresistant enterococci (VRE) infection or colonization (inf/col) were identified via routine clinical examinations and two nonroutine examinations from January to April 2007. Two case-control studies were conducted to identify the factors related to VRE inf/col. In study 1, the patients with VRE inf/col from ward A (n = 8) were compared with all of the patients without VRE isolates in the same ward, i.e., the controls (n = 26). In study 2, all adult patients with VRE inf/col throughout the hospital (n = 14) were compared with controls randomly selected from among all patients without VRE isolates (n = 45). All the subject cases were found to be infected or colonized with Enterococcus faecium, vanB. All but two of the isolated strains were completely identical according to pulsed field gel electrophoresis. Univariate analysis in study 2 showed several factors, including the isolation of methicillin-resistant Staphylococcus aureus (MRSA) (odds ratio [OR], 8.6; 95% confidence interval [CI], 1.3–53.7) and the use of antibiotics other than anti-MRSA drugs (OR, 33.0; 95% CI, 1.8–587.6) to be risk factors for VRE inf/col. Multivariate logistic regression analysis in study 2 demonstrated associations with VRE inf/col in the use of an ultrasound nebulizer (OR, 5.9; 95% CI, 1.5–22.8) and extended bed rest (OR, 3.8; 95% CI, 1.02–24.5). Although severe infection with VRE did not occur, to avoid the spread of VRE in hospital wards, further staff education should be implemented in regard to the usual standard and contact precautions, and the appropriate selection of antibiotics.