Role of MRSA reservoirs in the acute care setting

Nosocomial infection remains the most common complication of hospitalisation. Despite infection control efforts, nosocomial methicillin-resistant Staphylococcus aureus (MRSA) transmission continues to rise. The associated costs of increased hospital stay and patient mortality cause considerable burden to the health system.

This review sought to evaluate the role of reservoirs, particularly the environment and equipment commonly found in the clinical area, in the transmission of MRSA within the acute hospital. This review updates a review previously completed by the authors and published by the Joanna Briggs Institute (2002).

A systematic search for relevant published or unpublished literature was undertaken using electronic databases, the reference lists of retrieved papers and the Internet. This extended the search published in the original review.Databases searched included Medline (1966-August Week 1 2005), CINAHL (1982-August Week 1 2005), EMBASE (1996-Week 33), as well as the Cochrane Library (Issue 3, 2005) and the Joanna Briggs Institute Evidence Library (August 2005).

All research reports published between 1990 and August 2005 in the English language that focused on the role of the environment and equipment commonly found in the clinical area on the nosocomial MRSA transmission in adult, paediatric or neonatal acute care settings were considered.

Two reviewers assessed each paper against the inclusion criteria and a validated quality scale. Studies that scored less than the mean quality score were excluded from the review. Data extraction was undertaken using a tool designed specifically for this review. Statistical comparisons of findings were not possible, so findings are presented in a narrative form.

Forty-two papers met the review inclusion criteria, of which 18 obtained a quality score above the threshold and are included in this review. Seven studies reported general investigations of MRSA in the clinical environment and 11 studies explored specific environmental aspects. All studies used exploratory, descriptive or comparative designs. The evidence suggests that MRSA strains within the environment often match those found in patients within that environment. MRSA can be found in the air around MRSA colonised or infected patients. The degree of airborne contamination is significantly increased by activities that promote airflow. Although the site of MRSA colonisation or infection can influence the degree of environmental contamination, these data are inconsistent. Therefore, there is limited evidence for tailoring infection control interventions based on the sites of MRSA colonisation or infection. The evidence suggests that the type of materials used in clinical equipment can influence the effectiveness of cleaning techniques. Current routine cleaning practices, including conventional terminal cleaning, do not necessarily effectively eradicate MRSA from the environment. This review demonstrates that there is a link between the environment and hospital equipment and the transmission of MRSA within the acute hospital setting. Further well-designed research is urgently required to explore the efficacy of specific cleaning and decontamination methods, staff compliance with infection control practices and the range of factors that affect the incidence of MRSA contamination of the environment and equipment commonly found in the clinical area.