Understanding short-term transmission dynamics of methicillin-resistant Staphylococcus aureus in the patient room.

Abstract

OBJECTIVE\nLittle is known about the short-term dynamics of methicillin-resistant Staphylococcus aureus (MRSA) transmission between patients and their immediate environment. We conducted a real-life microbiological evaluation of environmental MRSA contamination in hospital rooms in relation to recent patient activity.\n\n\nDESIGN\nObservational pilot study.\n\n\nSETTING\nTwo hospitals, hospital 1 in Zurich, Switzerland, and hospital 2 in Ann Arbor, Michigan, United States.\n\n\nPATIENTS\nInpatients with MRSA colonization or infection.\n\n\nMETHODS\nAt baseline, the groin, axilla, nares, dominant hands of 10 patients and 6 environmental high-touch surfaces in their rooms were sampled. Cultures were then taken of the patient hand and high-touch surfaces 3 more times at 90-minute intervals. After each swabbing, patients hands and surfaces were disinfected. Patient activity was assessed by interviews at hospital 1 and analysis of video footage at hospital 2. A contamination pressure score was created by multiplying the number of colonized body sites with the activity level of the patient.\n\n\nRESULTS\nIn total, 10 patients colonized and/or infected with MRSA were enrolled; 40 hand samples and 240 environmental samples were collected. At baseline, 30% of hands and 20% of high-touch surfaces yielded MRSA. At follow-up intervals, 8 (27%) of 30 patient hands, and 10 (6%) of 180 of environmental sites were positive. Activity of the patient explained 7 of 10 environmental contaminations. Patients with higher contamination pressure score showed a trend toward higher environmental contamination.\n\n\nCONCLUSION\nEnvironmental MRSA contamination in patient rooms was highly dynamic and was likely driven by the patient s MRSA body colonization pattern and the patient activity.