620. Cefazolin Versus Ceftriaxone for the Treatment of Methicillin-Susceptible Staphylococcus aureus (MSSA) Bacteremia in a Tertiary-Care VA Medical Center
Session: Oral Abstract Session: Bacteremia and Endocarditis
Thursday, October 8, 2015: 2:00 PM
Room: 32--ABC
Background: Cefazolin and ceftriaxone are frequently used to treat methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, especially in the context of outpatient parenteral antimicrobial therapy (OPAT).   Both antibiotics have been associated with favorable clinical outcomes in settings of mixed MSSA infection. Limited published data exists, however, specifically comparing the use of these agents in the treatment of MSSA bacteremia. 

Methods: We conducted a retrospective cohort study of veteran patients diagnosed with MSSA bacteremia who received ≥ 14 days of parenteral cefazolin or ceftriaxone between 2009 and 2014.   Both patient and facility factors were reviewed.  Rates of treatment failure were compared between cefazolin and ceftriaxone at the end of therapy. Treatment failure was defined as therapy extension, incomplete therapy, unplanned oral suppressive therapy, relapse or recurrence of infection, or hospital admission or surgery within 90 days.

Results: Seventy-one patients were eligible for inclusion. 38 patients received treatment with cefazolin and 33 with ceftriaxone. The overall rate of treatment failure was 40.8% and there were significantly more failures among patients receiving ceftriaxone (54.5% vs. 28.9%; p=0.029). Other factors predictive of treatment failure included longer duration of parenteral therapy [OR 1.05 (CI 1.01 – 1.10); p=0.015], heart failure [OR 7.93 (CI 2.43 – 25.92); p<0.001, and treatment in an outside skilled nursing facility as compared with treatment in the VA Medical Center’s attached Community Living Center [71% vs. 17%; p=0.008], respectively.

Conclusion: We found that ceftriaxone had a higher rate of treatment failure than cefazolin for parenteral treatment of MSSA bacteremia in a high-acuity veteran population. Potential reasons for this could include the higher protein binding manifested by ceftriaxone, ultimately resulting in lower serum concentrations of free drug, dosing issues, or other unknown factors.  We also found that patients receiving their OPAT in a VA-supervised skilled nursing facility had lower rates of treatment failure than patients in community nursing facilities, possibly reflecting increased education of providers and easier access to consultant expertise.

Dustin Carr, Pharm.D.1, Robert A. Bonomo, MD2, Usha Stiefel, M.D.3 and Sharanie Sims, Pharm.D., BCPS (AQ-ID)1, (1)Pharmacy, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, (2)Pharmacology, Molecular Biology, and Microbiology, Case Western Reserve University, Cleveland, OH, (3)Medicine, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH


D. Carr, None

R. A. Bonomo, None

U. Stiefel, None

S. Sims, None

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