Program Schedule

Tracing the Natural History of Methicillin-Resistant Staphylococcus aureus (MRSA) Colonization among Residents of a Long Term Veterans’ Nursing Home in Pittsburgh, PA

Session: Poster Abstract Session: MRSA and VRE
Thursday, October 9, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC

Residing in long-term care facilities (LTCF) is a risk for MRSA carriage and infection. MRSA colonization rates up to 40% are reported, 3% to 50% of colonizers develop infections. In 2007, VA Pittsburgh Healthcare System (VAPHS) initiated universal screening for MRSA in LTCF patients. This afforded a unique opportunity to examine the natural history and consequences of MRSA carriage in LTCFs.


1. To assess MRSA colonization and infection over a 6 year period in a VA long term care facility

2. To identify risk factors for infection among those colonized with MRSA


This was an observational retrospective cohort study. Charts of all patients residing at the facility with a surveillance or clinical culture yielding MRSA during FY 2007 through FY 2012 were reviewed. Patients with prior or active staphylococcal infection were excluded. Patients were followed until death, discharge, transfer or up to September 2012.


359 patients were identified. 41% were MRSA positive on admission and 59% acquired MRSA during their stay at a median of 49 days post admission. Overall 15% acquired MRSA infections-10% of patients that were positive on admission and 18% of new MRSA patients. Factors associated with infection using multivariate analysis included: length of stay [LOS] >3 weeks [OR 8.10 (95% CI 1.9-35.4)], duration of MRSA carriage [1.003/day (1.002-1.005)], dementia [2.66 (1.3-5.3)], skin breakdown [3.98 (2.0-8.0)], female gender [4.73 (1.1-19.8)] and hemodialysis [3.72 (0.9-14.7)]. 14.5% died during the current admission. Mortality was related to age, underlying diseases and MRSA colonization at admission, but not MRSA infection. Use of antibiotics was not associated with MRSA infections or death. The rate of MRSA transmission during this time period averaged 0.89/1000 bed days of care.


Risk factors significant for MRSA infection are presence of wounds, dementia, hemodialysis, duration of MRSA carriage and prolonged length of stay which would be suitable targets for studies examining benefits of decolonization. The majority of infections in our long-term care facility occurred among those acquiring MRSA colonization after admission, despite an active MRSA prevention program and a low rate of transmission.

Gitanjali Pai, MD1, Marilyn Wagener, MPH2, Candace Cunningham, RN3, Cheryl Creen, RN MSN3, Diana Toy, RN BSN CIC3 and Robert Muder, MD4, (1)Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, PA, (2)University of Pittsburgh, Pittsburgh, PA, (3)VA Pittsburgh Healthcare System, Pittsburgh, PA, (4)VA Pittsburgh Healthcare System, University of Pittsburgh School of Medicine, Pittsburgh, PA


G. Pai, None

M. Wagener, None

C. Cunningham, None

C. Creen, None

D. Toy, None

R. Muder, None

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