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Experimental Endocarditis Model of Methicillin Resistant Staphylococcus aureus (MRSA) in Rat
Published on: June 4, 2012
Importance of the environment for patient acquisition of methicillin-resistant Staphylococcus aureus in the intensive
Andrew P Wilson1, Samantha Hayman, Tony Whitehouse
1Department of Clinical Microbiology, University College London Hospitals, London, UK.
Objective:
To assess the degree of environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) in critical care and the likelihood of subsequent new patient acquisition if carriers were or were not moved to single rooms.
Design:
Randomized sequential sampling of bed areas.
Setting:
Intensive care units of two teaching hospitals.
Patients:
Medical and surgical patients requiring critical care.
Interventions:
Six environmental sites around randomly selected patients plus two communal sites were sampled using contact plates during periods when patients with MRSA were physically isolated or not. Admission, weekly, and discharge screening patient swabs were taken to identify patients admitted with, or newly acquiring, MRSA.
Measurements And Main Results:
A total of 2,436 samples were taken from environments around 114 patients, plus a further 349 samples from doctors' hands and telephones. Of the 47 bed areas where MRSA strains were identified that were not found initially on patients, only one patient subsequently acquired the same strain. Five other patients became colonized with new MRSA strains, but these were not found in their environment beforehand. Of 52 patients colonized with MRSA, 34 had a similar strain found subsequently in their environment.
Conclusions:
Whereas the MRSA-colonized patient frequently contaminates his or her local environment, transmission of MRSA from the environment to the patient was not commonly identified. Studies elucidating possible routes of MRSA transmission are urgently needed to inform infection control policies.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) colonization frequently contaminates the patient environment. However, environmental transmission to new patients was uncommon, suggesting a need for further research into MRSA transmission routes.
Area of Science:
- Infection Control and Hospital Epidemiology
- Clinical Microbiology
- Critical Care Medicine
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant healthcare-associated pathogen.
- Understanding environmental contamination and patient acquisition is crucial for effective infection control in critical care settings.
Purpose of the Study:
- To quantify environmental contamination with MRSA in intensive care units (ICUs).
- To assess the likelihood of new patient acquisition of MRSA from the environment.
- To evaluate the impact of patient isolation on MRSA transmission.
Main Methods:
- Randomized sequential sampling of environmental sites around ICU patients.
- Contact plate sampling of bed areas, doctors' hands, and telephones.
- Patient screening swabs (admission, weekly, discharge) to identify MRSA colonization and acquisition.
Main Results:
- MRSA was frequently found in the environment of colonized patients.
- Environmental MRSA strains were rarely linked to new patient acquisition.
- Most new MRSA acquisitions by patients were not preceded by environmental contamination with the same strain.
Conclusions:
- While MRSA-colonized patients contaminate their environment, direct environmental-to-patient transmission appears infrequent.
- Further research is needed to identify the primary routes of MRSA transmission.
- Findings emphasize the need for updated infection control strategies in critical care.
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