562. Long Term Persistence of the Non-colonized with Nasal MRSA Pattern Among Hospitalized Veterans
Session: Poster Abstract Session: MRSA Surveillance and Infection Prevention
Friday, October 21, 2011
Room: Poster Hall B1
Background: Understanding the epidemiology of nasal carriage of MRSA is important for optimizing infection prevention practices. The VA MRSA Initiative includes active surveillance for MRSA on every hospital admission. This prevention program, coupled with the electronic medical record (EMR), provides an opportunity to evaluate nasal MRSA carriage patterns in hospital-exposed veterans.  

Methods: We conducted a retrospective cohort study of veterans admitted to 5 acute care VA hospitals in New England over a 3-year period (1/08-12/10).  Any patient with a nasal MRSA PCR screen within 48 hours of the index admission and a second nasal PCR screen within 30 days of the first test was eligible to be included. The EMR was used to capture antibiotic and health care exposures and co-morbidities. Carriage pattern was based on 2 or more nasal PCR results and coded as never (0 positive), intermittent (>0, <.80 positive), and always (≥.80 positive).

Results: A total of 20,305 unique patients were eligible. At 30 days, the carriage pattern distribution was 18,593 (91.6%) never, 860 (4.2%) intermittent, and 852 (4.2%) always colonized. Compared to never colonized patients, a greater proportion of always colonized patients were >70 years of age (54% vs. 39%), hospitalized in the previous year (38% vs. 16%), had an MRSA infection in the previous year (4.2% vs. 0.18%), had co-morbidities (renal, lung, or skin disease, decubitus ulcer, diabetes), and antibiotic exposure in the previous 6 months. Among the 18,593 patients who were originally classified as never colonized, 7,580 were re-tested during the remaining study period (between day 30 and 719), and 87% remained negative.

Conclusion: Although many studies have evaluated continued MRSA colonization in previously positive patients, few have studied a persistently negative group. A large proportion of veterans who are negative for MRSA nasal colonization within 30 days of acute hospitalization remain negative for a prolonged period, despite re-hospitalization and re-testing. Our data suggest that continued active surveillance for MRSA among patients who are negative at 30 days from initial hospital admission may not be necessary or could be risk-based, markedly reducing the number of screening tests performed over time.

Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

Kalpana Gupta, MD, MPH1,2, Melissa Young2,3, Judith Strymish, MD1,4, Richard Martinello, MD5,6, Galina Sokolovskaya2,3, Kelly Cho, PhD2,3 and Elizabeth Lawler, PhD2,3, (1)VA Boston Health Care System, West Roxbury, MA, (2)Massachusetts Veterans Epidemiology Research and Information Center, Jamaica Plain, MA, (3)VA Cooperative Studies, Jamaica Plain, MA, (4)Harvard Medical School, West Roxbury, MA, (5)Veterans Health Administration, Office of Public Health, (Center for Occupational Health and Infection Control), West Haven, CT, (6)Yale University School of Medicine, West Haven, CT


K. Gupta, None

M. Young, None

J. Strymish, None

R. Martinello, None

G. Sokolovskaya, None

K. Cho, None

E. Lawler, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.