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Open Access Highly Accessed Research article

Nursing home characteristics associated with methicillin-resistant Staphylococcus aureus (MRSA) Burden and Transmission

Courtney R Murphy1*, Victor Quan1, Diane Kim1, Ellena Peterson2, Matthew Whealon1, Grace Tan2, Kaye Evans2, Hildy Meyers3, Michele Cheung3, Bruce Y Lee4, Dana B Mukamel5 and Susan S Huang1

Author affiliations

1 Division of Infectious Diseases and Health Policy Research Institute, University of California Irvine School of Medicine, Irvine, USA

2 Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Irvine, USA

3 Epidemiology and Assessment Program, Orange County Health Care Agency, Santa Ana, USA

4 Department of Medicine, Epidemiology and Biomedical Informatics, University of Pittsburgh School of Medicine and Graduate School of Public Health, Pittsburgh, USA

5 Department of Medicine and Health Policy Research Institute, University of California Irvine School of Medicine, Irvine, USA

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Citation and License

BMC Infectious Diseases 2012, 12:269  doi:10.1186/1471-2334-12-269

Published: 24 October 2012

Abstract

Background

MRSA prevalence in nursing homes often exceeds that in hospitals, but reasons for this are not well understood. We sought to measure MRSA burden in a large number of nursing homes and identify facility characteristics associated with high MRSA burden.

Methods

We performed nasal swabs of residents from 26 nursing homes to measure MRSA importation and point prevalence, and estimate transmission. Using nursing home administrative data, we identified facility characteristics associated with MRSA point prevalence and estimated transmission risk in multivariate models.

Results

We obtained 1,649 admission and 2,111 point prevalence swabs. Mean MRSA point prevalence was 24%, significantly higher than mean MRSA admission prevalence, 16%, (paired t-test, p<0.001), with a mean estimated MRSA transmission risk of 16%.

In multivariate models, higher MRSA point prevalence was associated with higher admission prevalence (p=0.005) and higher proportions of residents with indwelling devices (p=0.01). Higher estimated MRSA transmission risk was associated with higher proportions of residents with diabetes (p=0.01) and lower levels of social engagement (p=0.03).

Conclusions

MRSA importation was a strong predictor of MRSA prevalence, but MRSA burden and transmission were also associated with nursing homes caring for more residents with chronic illnesses or indwelling devices. Frequent social interaction among residents appeared to be protective of MRSA transmission, suggesting that residents healthy enough to engage in group activities do not incur substantial risks of MRSA from social contact. Identifying characteristics of nursing homes at risk for high MRSA burden and transmission may allow facilities to tailor infection control policies and interventions to mitigate MRSA spread.

Keywords:
MRSA; Healthcare-associated infection; Long-term care; Nursing home