Outbreak of vancomycin-resistant Enterococcus faecium in a haematology unit: risk factor assessment and successful control of the epidemic

We describe an outbreak of vancomycin-resistant Enterococcus faecium (VRE) on the haematology ward of a Dutch university hospital. After the occurrence of three consecutive cases of bacteraemia with VRE, strains were genotyped and found to be identical. During the next 4 months an intensive surveillance programme identified 21 additional patients to be colonized with VRE, while two more patients developed bacteraemia. A case-control study was carried out to identify risk factors for VRE acquisition. In comparison with VRE-negative control patients (n=49), cases (n=24) had a longer stay on the ward during the year preceding the outbreak (25.8 versus 10.1 d, P=0.02), more cases with acute myeloid leukaemia [11 versus 4, odds ratio (OR) 9.5, 95% confidence interval (CI95) 2.4-32.2] and higher grades of mucositis (P=0.03). Logistic regression analysis identified antibiotic use within 1 month before admission (OR 13.0, CI95 2.1-80.5, P=0.006) and low albumin levels at baseline (OR 1.2, CI95 1.1-1.3, P=0.02) to be independent risk factors. Four patients with VRE-bacteraemia were successfully treated with quinupristin/dalfopristin (Synercid). Control of the outbreak was achieved by step-wise implementation of intensive infection control measures, which included the cohorting of patients, allocation of nurses and reinforcement of hand hygiene.