Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment

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Abstract

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (P<0.0001). Gram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (P<0.0001) and hospital personnel (P=0.1145). Environmental contamination did not differ between the intensive care units (ICUs) and the general wards (GWs), which is noteworthy because our ICUs are routinely disinfected twice a day, whereas GWs are cleaned just once a day with detergent. Current guidelines for the prevention of spread of multi-resistant bacteria in the hospital setting do not distinguish between Gram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources.

Introduction

The increasing emergence and spread of multi-resistant bacteria in hospitals is of great concern and continues to challenge infection control and hospital epidemiology practice worldwide.1., 2., 3., 4. The frequency of cross-transmission varies between 13 and 34.6%, and is especially high in intensive care units (ICUs).5., 6., 7., 8. Rigorous isolation guidelines have been proposed to prevent cross-transmission of multi-resistant bacteria, without distinguishing between Gram-positive and Gram-negative organisms.9., 10., 11., 12., 13., 14. Contamination of the hospital inanimate environment by Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE), especially in an epidemic situation, has been frequently addressed.15., 16., 17., 18., 19. Micro-organisms in the inanimate hospital environment are said to contribute only negligibly to endemic nosocomial infections.20., 21., 22., 23. However, limited data are available concerning the degree of contamination of the hospital environment of patients harbouring multi-resistant Gram-negative organisms compared with Gram-positive organisms. Strict isolation is time-consuming, expensive and causes considerable discomfort for patients and hospital personnel.4., 24. Therefore, in order to improve the current situation these recommendations must be evaluated by prospective studies. The aim of this study was: (1) to assess the degree of contamination of hospital rooms and the patients' inanimate environment with multi-resistant Gram-negative and Gram-positive bacteria; (2) to discuss the role played by these bacteria in cross-transmission; and (3) to evaluate current isolation precautions in light of these findings.

Section snippets

Setting

The University Hospital Aachen is a tertiary care teaching hospital with around 1500 beds. Annually, approximately 48 000 patients are admitted and account for 470 000 patient bed-days. This study was performed in nine ICUs (anaesthetics, burns unit, cardiac surgery, internal medicine, neurology, neurosurgery, paediatric and general surgery) with 101 beds. Additionally, all the general wards (GWs) were studied. Surfaces in the ICUs (floor, walls and all easily accessible items) were disinfected

Results

One hundred and ninety patients who were either colonized or infected with MRSA, VRE or multi-resistant Gram-negative bacteria were consecutively enrolled and monitored during the study. Fifty-four patients (28.4%) harboured multi-resistant Gram-positive bacteria and 136 (71.6%), multi-resistant Gram-negative bacteria (see Table I). The mean hospital stay before the microbiological isolation and the environmental sampling was 7.3 and 19.4 days for Gram-positive and Gram-negative isolates,

Discussion

We have clearly demonstrated that the degree of environmental contamination with multi-resistant Gram-positive organisms (e.g. MRSA and VRE) was much more extensive than for multi-resistant Gram-negative pathogens (24.7 versus 4.9%, P<0.0001). During the study period, the average prevalence for MRSA was 0.13 MRSA-positive patients per 1000 patient days. As no outbreak or cluster was observed during this time, this extremely low prevalence suggests that the environmental samples found were

References (41)

  • D. Talon

    The role of the hospital environment in the epidemiology of multi-resistant bacteria

    J Hosp Infect

    (1999)
  • S.S. Bukhari et al.

    Endemic cross-infection in an acute medical ward

    J Hosp Infect

    (1993)
  • P. Gastmeier et al.

    Guidelines for infection prevention and control in Germany: evidence- or expert-based?

    J Hosp Infect

    (1999)
  • M. Farrington et al.

    Effects on nursing workload of different methicillin-resistant Staphylococcus aureus (MRSA) control strategies

    J Hosp Infect

    (2000)
  • E. Larson

    Compliance with isolation technique

    Am J Infect Control

    (1983)
  • M.S. Arnold et al.

    The best hospital practices for controlling methicillin-resistant Staphylococcus aureus: on the cutting edge

    Infect Control Hosp Epidemiol

    (2002)
  • M. Farrington et al.

    Controlling MRSA

    J Hosp Infect

    (1999)
  • D.A. Goldmann et al.

    Control of nosocomial antimicrobial-resistant bacteria: a strategic priority for hospitals worldwide

    Clin Infect Dis

    (1997)
  • P. Chetchotisakd et al.

    Assessment of bacterial cross-transmission as a cause of infections in patients in intensive care units

    Clin Infect Dis

    (1994)
  • K. Weist et al.

    How many nosocomial infections are associated with cross-transmission? A prospective cohort study in a surgical intensive care unit

    Infect Control Hosp Epidemiol

    (2002)
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