511. Clinical Significance of Positive Sternal Swabs at Time of Delayed Sternal Closure
Session: Poster Abstract Session: Surgical Site Infections
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Cardiac surgeons at SCH began routinely obtaining swabs of the mediastinum at the time of delayed sternal closure in December 2006.  We evaluated the clinical significance of culture-positive sternal swabs.

Methods: The medical records of all patients with delayed sternal closure performed between December 2006 and December 2011 were reviewed. Clinical characteristics, swab culture data, and surgical site infection (SSI) data were obtained. SSIs were identified prospectively by Infection Prevention using NHSN criteria. Multivariate logistic regression was preformed to evaluate potential risk factors for SSI as well as predictors for positive sternal swabs. Variables with a univariate p value <0.1 were considered eligible for the multivariate model.

Results: A total of 137 patients had delayed sternal closure during the study period; sternal swabs were obtained on 132 patients.  Among these 132 patients, 22 (17%) had a positive sternal swab.

SSI developed in 27% of the positive swab group vs 5% of the negative swab group (p=0.003). The only univariate predictor for SSI was presence of a positive sternal swab (OR; 7.88, 95% CI 2.15-28.84, p=0.02). Given the lack of other predictive factors, and the small number of SSIs, multivariate analysis was not performed.

Univariate predictors for positive sternal swab included age at surgery >2 weeks, prematurity, non-cardiac comorbidity, and extracorporeal membrane oxygenation (ECMO) prior to sternal closure. In multivariate analysis, prematurity (OR; 3.04, 95% CI 0.98-8.43, p=0.03) and ECMO (OR; 2.86, 95% CI 1.12-8.25, p=0.05) were independent predictors for a positive sternal swab.

Gram-negative pathogens were identified in 83% of the SSIs in the positive swab group vs 20% in the negative swab group (p=0.08). SSIs in the positive swab group were identified a mean 2.3 days after sternal closure vs 10.2 days in the negative swab group (p=0.06). All SSIs were categorized as organ/space.

Conclusion: Patients with positive sternal swabs had a significantly higher rate of subsequent SSI and a positive swab was the only statistically significant predictor of SSI. Prematurity and placement on ECMO prior to sternal closure were independently associated with a positive sternal swab at delayed closure.

Amanda Adler, BA1, Julie Smith, RN2, Lester Permut, MD3, Michael Mcmullan, MD3 and Danielle Zerr, MD, MPH1,4, (1)Seattle Children's Hospital Research Institute, Seattle, WA, (2)Children's Hospital and Regional Medical Center, Seatte, WA, (3)Pediatric Cardiothroacic Surgery, University of Washington, Seattle, WA, (4)Department of Pediatrics, University of Washington, Seattle, WA


A. Adler, None

J. Smith, None

L. Permut, None

M. Mcmullan, None

D. Zerr, None

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