1731. Treatment Outcomes of Cefazolin versus Oxacillin for High Burden Methicillin-Sensitive Staphylococcus aureus (MSSA) Bloodstream Infections (BSI)
Session: Poster Abstract Session: Treatment of Bacteremia and Endocarditis
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Background: For many clinicians, antistaphylococcal penicillins (i.e. oxacillin or nafcillin) are the preferred treatment for MSSA BSI. Cefazolin is a more convenient alternative treatment for MSSA BSI, but some are concerned about potentially higher failure rates with cefazolin because of possible inoculum effect with β-lactamase A-producing MSSA isolates. The aim of this study was to assess the clinical outcomes of patients treated with cefazolin (CEF) or oxacillin (OX) for MSSA BSI, including those with high burden disease (i.e. endocarditis and endovascular infections).  

Methods: A retrospective, multi-centered observational study was conducted. Adult patients from author institutions with a MSSA BSI between 01/2010 and 08/2012 treated with CEF or OX within 48 hours of finalized culture results were considered for analysis. Polymicrobial infections and patients with penicillin allergies were excluded. Variables for assessment included: baseline demographics, treatment regimen, time to first negative blood culture, source of infection, APACHE II score, length of hospitalization, and treatment outcome. The primary endpoint of the study was clinical cure versus treatment failure. Secondary endpoints included time to death, duration of bacteremia, adverse events, in-hospital mortality, and clinical outcome of high burden diseases. Backward stepwise logistic regression was performed to predict risk of treatment failure

Results: 127 patients with MSSA BSI were included: 95 were treated with CEF and 32 with OX. Baseline characteristics were well balanced between the groups. The most common sources of MSSA BSI were central line and bone/joint infections. 33.7% of CEF and 25% of OX-treated infections were considered high burden. Overall, treatment with OX predicted increased failure (OR 4.9, 95% CI 1.44-16.3) after controlling for APACHE II score and ICU status.  No difference was seen in high burden infections. Mortality was observed in 1 CEF and 3 OX-treated individuals. The rates of adverse drug events for CEF and OX were similar [7.3% and 6.3%, respectively (p=0.76)].

Conclusion: Cefazolin is no worse than oxacillin for MSSA BSI, including treatment of high-burden infections. We recommend more robust studies to validate our findings.

Sonia Nevrekar, PharmD, BCPS1,2, Nathaniel Rhodes, PharmD, BCPS1,3, Christopher Crank, PharmD,2, Marc Scheetz, PharmD, MSc, BCPS AQ-ID3, Amy Pavell, PharmD, BCPS2, John Segreti, MD2 and Sheila Wang, PharmD, BCPS AQ-ID2, (1)Pharmacy Practice, Midwestern University, Chicago College of Pharmacy, Downers Grove, IL, (2)Rush University Medical Center, Chicago, IL, (3)Northwestern Memorial Hospital, Chicago, IL

Disclosures:

S. Nevrekar, None

N. Rhodes, None

C. Crank, None

M. Scheetz, None

A. Pavell, None

J. Segreti, None

S. Wang, None

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