Isolation and characterization of glycopeptide-resistant enterococci from hospitalized patients over a 30-month period

Abstract

In February 1996, a Hospital Infection Control Practices Advisory Committee-style screening program was commenced to isolate and subsequently characterize glycopeptide-resistant enterococci (GRE) from patients at a hospital trust in Glasgow, Scotland. Over the next 30 months, GRE were isolated from 154 patients. GRE were isolated from patients in traditionally high-risk areas such as the renal unit and intensive care unit and also in areas considered to be lower risk, including medical wards and associated long-stay geriatric hospitals. The majority (90%) of isolates were Enterococcus faecium vanB. The remaining isolates consisted of seven E. faecalis (vanA), three E. gallinarum (vanC), and a further six E. faecium (five vanA, one both vanA and vanB) isolates. Analysis of SmaI-digested DNA by pulsed-field gel electrophoresis revealed that 34 of 40 (85%) VanB E. faecium isolates were identical or closely related, while 11 of 13 (85%) VanA GRE were distinct. High-level aminoglycoside resistance was seen in less than 8% of isolates. VanB E. faecium isolates were almost uniformly resistant to ampicillin and tetracycline. In this study, GRE have been isolated over a prolonged period from a broad range of patients. Glycopeptide resistance within the study hospital trust appeared to be mainly due to the clonal dissemination of a single strain of E. faecium VanB.