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Natural History of Colonization With Vancomycin-Resistant Enterococci, Methicillin-Resistant Staphylococcus Aureus, And Resistant Gram-Negative Bacilli Among Long-Term–Care Facility Residents

Published online by Cambridge University Press:  02 January 2015

Glenn A. Pacio
Division of Infectious Diseases, New York Medical College, Valhalla, New York
Paul Visintainer
Graduate School of Health Sciences, New York Medical College, Valhalla, New York
George Maguire
Division of Pulmonary Medicine, Department of Medicine, New York Medical College, Valhalla, New York
Gary P. Wormser
Division of Infectious Diseases, New York Medical College, Valhalla, New York
John Raffalli
Division of Infectious Diseases, New York Medical College, Valhalla, New York
Marisa A. Montecalvo*
Division of Infectious Diseases, New York Medical College, Valhalla, New York
Division of Infectious Diseases, New York Medical College, Munger Pavilion 320, Valhalla, NY 10595



To determine the natural history of colonization with vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and resistant gram-negative bacilli among long-term–care facility (LTCF) residents.


Observational cohort study.


A 355-bed LTCF with a ventilator unit and a subacute unit.


Residents with colonization or infection with VRE, MRSA or resistant gram-negative bacilli housed at the LTCF between December 1,1999, and February 29, 2000.


Cultures of clinical and surveillance sites were performed at regular intervals. Charts were reviewed for clinical characteristics associated with clearance of colonization. Kaplan–Meier curves were constructed to analyze the number of days to clearance of colonization.


Forty-nine residents had 65 episodes of colonization (27 VRE, 30 MRSA and 8 resistant gram-negative bacilli). Eighteen (28%) of the episodes cleared. The clearance rate was 2.7 episodes per 1,000 person-days. Clearance occurred significantly more often with resistant gram-negative bacilli colonization compared with VRE or MRSA colonization (6 [75%] vs 12 [21%]; P = .007; relative risk, 4.17; 95% confidence interval, 1.26 to 11.8). There was a trend toward longer use of antimicrobial agents among residents with persistent colonization. Infections occurred most frequently with MRSA The urinary tract was the most common site of infection.


Among LTCF residents, colonization with resistant gram-negative bacilli is four times more likely to clear than colonization with VRE or MRSA. Performance of surveillance cultures at regular intervals may reduce the need for contact precautions for LTCF residents with resistant gram-negative bacilli colonization.

Original Articles
Copyright © The Society for Healthcare Epidemiology of America 2003

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