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Prior Hospital-Room Occupants: A Source of Antibiotic-Resistant Bacteria

The risk for transmission increases if the prior occupant was positive for such organisms.

In-hospital transmission of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) contributes substantially to morbidity and mortality. In a retrospective study of patients admitted to eight ICUs (medical and surgical) at a tertiary medical center over 20 months, researchers assessed the risk for acquiring MRSA or VRE if the room's prior occupant was positive for either organism.

Nares cultures for MRSA and rectal cultures for VRE were performed for all patients at admission and weekly. Patients were excluded if they had a history of MRSA or VRE, or if they tested positive within 48 hours of admission.

Of more than 10,000 patients, 14% were admitted to a room in which the prior occupant was MRSA-positive. These patients had a significantly higher risk for acquiring MRSA than patients admitted to a room in which the prior occupant was MRSA-negative (3.9% vs. 2.9%). These cases represented 5.1% of all ICU MRSA acquisitions during the study period. Similarly, the 13% of ICU patients who were admitted to a room in which the prior occupant was VRE-positive had a higher risk for acquiring VRE (4.5% vs. 2.8%), and these cases represented 6.8% of all ICU VRE acquisitions.

Comment: This retrospective study shows that the risk for acquiring MRSA or VRE increases if the hospital room was previously occupied by a patient who was positive for the organism. Although this mode of transmission accounted for well under 10% of MRSA and VRE acquisitions, the study documents the importance of environmental sources of antibiotic-resistant organisms.

— Jamaluddin Moloo, MD, MPH

Published in Journal Watch General Medicine November 2, 2006

Citation(s):

Huang SS et al. Risk of acquiring antibiotic-resistant bacteria from prior room occupants. Arch Intern Med 2006 Oct 9; 166:1945-51.

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