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Methicillin‐Resistant Staphylococcus aureus Burden in Nursing Homes Associated with Environmental Contamination of Common Areas



To determine whether environmental cleaning and contamination are associated with variation in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) between nursing homes.


Prospective study of environmental contamination and cleaning quality.


Nursing home.


Ten California nursing homes.


Nursing homes were categorized into two groups based upon high and low differences in MRSA point prevalence and admission prevalence (delta prevalence) from nares screenings of nursing home residents. Environmental cleaning and infection control practices were evaluated by culturing common area objects for MRSA, assessing removal of intentionally applied marks visible only under ultraviolet (UV) light, and administering surveys on infection control and cleaning.


Overall, 16% (78/500) of objects were MRSA positive, and 22% (129/577) of UV-visible marks were removed. A higher proportion of MRSA-positive objects was found in the high (19%) than in low (10%) nursing home groups (P = .005). Infection control and cleaning policies varied, including the frequency of common room cleaning (median 2.5 times daily, range 1-3 times daily) and time spent cleaning per room (median 18 minutes, range 7-45 minutes). In multivariate models, MRSA-positive objects were associated with high delta prevalence nursing homes (odds ratio (OR) = 2.8, P = .005), less time spent cleaning each room (OR = 2.9, P < .001), and less-frequent cleaning of common rooms (OR = 1.5, P = .01).


Substantial variation was found in MRSA environmental contamination, infection control practices, and cleaning quality. MRSA environmental contamination was associated with greater differences between MRSA point and admission prevalence, less-frequent common room cleaning, and less time spent cleaning per room, which suggests that modifying cleaning practices may reduce MRSA environmental contamination and burden in nursing homes.

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