Methicillin-resistant Staphylococcus aureus colonization in a long-term-care facility.

OBJECTIVE: To study the prevalence and risk factors for colonization with MRSA at a long-term-care facility.

DESIGN: Cross-sectional surveillance culture survey.

SETTING: A 233-bed university-affiliated long-term-care facility.

MEASUREMENTS: Surveillance cultures for MRSA were performed on patients of two adjacent nursing units and on new admissions to the entire facility over a 4-month period.

RESULTS: On the chronic medical unit, where patients known to be colonized had been cohorted, 20 of 38 (52.6%) were colonized vs 3 of 67 (4.5%) on the skilled/intermediate unit (P less than 0.001), suggesting that little intra-facility spread of MRSA occurs. Twenty-four of 55 (43.6%) chronic medical admissions were colonized vs 6 of 63 (9.5%) admitted to the other units (P less than 0.001). Thirteen of 30 (43.3%) admissions were not previously known to be colonized. By univariate analysis, colonized admissions were younger and more often male; had more listed diagnoses, including pressure sores, a previous positive MRSA culture, and urinary incontinence; were more often fed by feeding tube; and had longer durations of hospital stay prior to admission. Logistic regression analysis showed that the most powerful independent predictors of colonization at admission were: a prior positive culture for MRSA (OR 8.8, 95% CI 2.4, 32.4), male sex (OR 8.2, 95% CI 2.3, 29.7), urinary incontinence (OR 3.8, 95% CI 1.4, 10.4), and presence of pressure sores (OR 2.9, 95% CI 0.9, 9.2).

CONCLUSIONS: Unrecognized colonization of nursing home residents with MRSA is common, and nursing homes are unwittingly repositories for patients colonized with MRSA following acute hospitalization. Gloving and careful attention to handwashing may limit spread of MRSA within nursing homes, and identification of colonized patients may be facilitated by targeted surveillance cultures of the most debilitated patients at admission.