Elsevier

The Lancet

Volume 348, Issue 9042, 14 December 1996, Pages 1615-1619
The Lancet

Articles
Epidemiology of colonisation of patients and environment with vancomycin-resistant enterococci

https://doi.org/10.1016/S0140-6736(96)02331-8Get rights and content

Summary

Background

Vancomycin-resistant enterococci (VRE) have emerged as nosocomial pathogens during the past 5 years, but little is known about the epidemiology of VRE. We investigated colonisation of patients and environmental contamination with VRE in an endemic setting to assess the importance of different sources of colonisation.

Methods

Between April 12, and May 29, 1995, cultures from body sites (rectum, groin, arm, oropharynx, trachea, and stomach) and from environmental surfaces (bedrails, drawsheet, blood-pressure cuff, urine containers, and enteral feed) were obtained daily from all newly admitted ventilated patients in our medical intensive-care unit (MICU). Rectal cultures were obtained from all non-ventilated patients in the MICU. Strain types of VRE were determined by pulsed-field gel electrophoresis.

Findings

There were 97 admissions of 92 patients, of whom 38 required mechanical ventilation. Colonisation with VRE on admission was more common in ventilated than in non-ventilated patients (nine [24%] vs three [6%], p<0·05). Of the nine ventilated patients colonised with VRE on admission, one acquired a new strain of VRE in the MICU. Of the 29 ventilated patients who were not colonised with VRE on admission, 12 (41%) acquired VRE in the MICU. The median time to acquisition of VRE was 5 days (interquartile range 3–8). Of the 13 ventilated patients who acquired VRE, 11 (85%) were colonised with VRE by cross-colonisation. VRE were isolated from 157 (12%) of 1294 environmental cultures. The rooms of 13 patients were contaminated with VRE, but only three (23%) of these patients subsequently acquired colonisation with VRE. Pulsed-field gel electrophoresis of 262 isolates showed 20 unique strain types of VRE.

Interpretation

Frequent colonisation with VRE on MICU admission and subsequent cross-colonisation are important factors in the endemic spread of VRE. Persistent VRE colonisation in the gastrointestinal tract and on the skin, the presence of multiple-strain types of VRE, and environmental contamination may all contribute to the spread of VRE.

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.

Section snippets

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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