N9. MRSA, MSSA and other gram positive pathogens
Oral Abstract Submission
Karim Khader, PhD
Research Assistant Professor
IDEAS Center of Innovation, VA Salt Lake City Health Care System
Salt Lake City, UT
Disclosure: Nothing to disclose
Alun Thomas, PhD
Professor
Division of Epidemiology, University of Utah School of Medicine, Salt Lake City, UT
Salt Lake City, UT
Disclosure: Nothing to disclose
Lindsay D. Visnovsky, PhD, MS
Research Assistant Professor
University of Utah
Salt Lake City, UT
Disclosure: Nothing to disclose
Damon Toth, PhD
Research Assistant Professor
IDEAS Center of Innovation, VA Salt Lake City Health Care System
Salt Lake City, UT
Disclosure: Nothing to disclose
Lindsay T. Keegan, PhD
Research Assistant Professor
Division of Epidemiology, University of Utah School of Medicine, Salt Lake City, UT
Salt Lake City, UT
Disclosure: Nothing to disclose
Makoto M. Jones, MD, MS
Associate Professor
University of Utah
Salt Lake City, UT
Disclosure: Nothing to disclose
Michael Rubin, MD/PhD
Professor
IDEAS Center of Innovation, VA Salt Lake City Health Care System
Salt Lake City, Utah
Disclosure: Nothing to disclose
Matthew H. Samore, MD
Director
VA Salt Lake City Healthcare System
Salt Lake City, Utah
Disclosure: Nothing to disclose
Background : In 2007, the Department of Veterans Affairs (VA) implemented the methicillin-resistant Staphylococcus aureus (MRSA) Prevention Initiative nationally in acute care facilities (ACFs). The initiative included universal nasal surveillance for MRSA colonization and implementation of contact precautions (CP) for identified carriers for the duration of their stay. Despite subsequent declines in MRSA infection rates in the VA, debate on CP efficacy continues, due to limited and inconclusive direct evidence. This study estimated CP impact on MRSA transmission in the VA.
Methods : We analyzed one year of data from 36 VA ACFs in 2014 using a Bayesian transmission model. The data included admission, discharge, and surveillance and clinical test results for MRSA. Per the MRSA Prevention Initiative protocol that placed known carriers on CP, we assumed patients were on CP starting 12 hours after a positive surveillance test, 24 hours after a positive clinical culture, or at admission if the patient had a positive test within 365 days prior to admission. Our model produced estimates of ward-specific transmission rate, surveillance test sensitivity, importation probability, and the CP effect parameter (CPe). For CPe < 1, CP reduced transmission. Additionally, we combined the estimates of CPe using a random effects model with inverse variance weights to derive pooled estimates and corresponding standard errors.
Results : Facility size varied with a median daily census of 70 patients per day (range: 44 – 111). During the study period, 144,386 individuals were admitted into one of 36 ACFs, for 215,207 total admissions. The median percentage of admissions requiring contact precautions was 11.0% (range: 6.4% - 16.1%). The estimated CPe was less than one in each of the 36 facilities with a median of 0.43 (range: 0.25 – 0.68). Our pooled estimate of CPe across all facilities was 0.47 (95% CI; 0.40, 0.55).
Conclusion : We found evidence of reduced MRSA transmission from patients on CP. This result was statistically significant in 5 of the 36 facilities and our pooled estimate suggests contact precautions could reduce the transmission rate by half. Further work is needed to account for imperfect compliance with CP, and for patients on CP for other reasons.
