ArticlesEpidemiology of colonisation of patients and environment with vancomycin-resistant enterococci
Introduction
Antibiotic resistance among nosocomial pathogens is a worldwide health-care issue. During the past 5 years, the emergence of vancomycin-resistant enterococci (VRE) has been a cause of especial concern. VRE were first reported in Europe, and the incidence of infections caused by these pathogens has increased substantially in the USA during the past few years.1, 2, 3 Little is known about the epidemiology of VRE, and most information is derived from descriptions of monoclonal outbreaks.4, 5, 6, 7, 8 However, VRE may not be confined to clinical cultures,9 and endemic colonisation may already be established in many hospitals.10 The reasons for the rapid emergence of VRE have not yet been investigated.
In this study, we investigated colonisation of patients and environmental contamination with VRE in a medical intensive-care unit (MICU), in which colonisation with VRE was known to be endemic, to identify the main sources of VRE.
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Setting and study design
Cook County Hospital is a public teaching hospital with beds for 900 patients. The MICU has 16 beds—12 in single rooms and four in double rooms. Between April 12, and May 29, 1995, we carried out a surveillance study of all mechanically ventilated patients in the MICU and obtained cultures from various body and environmental sites daily.
We decided to focus on mechanically ventilated patients because most non-ventilated patients are discharged from the MICU within 2 days of admission. In
Results
During the 7-week study, there were 97 admissions of 92 patients (52 women, 40 men). The bed occupancy rate was 90%. 38 patients (21 women, 17 men) received mechanical ventilation. The median age of ventilated patients was 48 years (interquartile range 34–60). 18 ventilated patients were admitted directly from the community and 20 had been in hospital before admission to the MICU for a median of 3 days (2–11). Surveillance of ventilated patients was for a median of 5 days (3–13). We collected
Discussion
Colonisation with VRE was highly endemic and polyclonal in our MICU—21 (55%) of 38 ventilated patients were colonised with VRE and 20 different strains of VRE were identified. We found that acquisition of VRE by cross-colonisation was an important factor in the spread of VRE. In 85% of cases of acquired colonisation, at least one other patient was colonised at the same time with an identical strain type of VRE. We also found that admission of previously colonised patients to the MICU had a
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