Comparison of Nafcillin and Cefazolin for the Treatment of Methicillin-Susceptible Staphylococcus aureus Bacteremia

Abstract

Background: Traditionally, the antibiotic of choice for Methicillin-susceptible Staphylococcus aureus related blood stream infections (MSSA-BSI) are the antistaphylococcal penicillins. Cefazolin is considered an alternative agent, with recent evidence showing similar clinical efficacy. This study further evaluates the utility of nafcillin versus cefazolin in MSSA bacteremia including high disease burden sources of infection and its impact on treatment failure.

Methods: This retrospective study included patients admitted to Methodist LeBonheur Healthcare adult hospitals from 2011 to 2016. Patients were included if they received at least 3 days of either nafcillin or cefazolin and had a positive blood culture for MSSA. The primary objective was to evaluate rates of treatment failure between groups. Secondary outcomes included clinical and microbiological cure, MSSA-BSI associated readmissions, identification of risk factors for treatment failure including disease burden, in-hospital and 90 day mortality.

Results: A total of 277 patients were included (nafcillin n = 126; cefazolin n = 151). Treatment failure and microbiologic cure were similar between nafcillin and cefazolin (20.6% vs. 16.6%; 91.2% vs. 87.2%, respectively). Clinical cure was significantly higher in the cefazolin treatment arm (93.4 vs. 83.3%; P = 0.012). However, the total number of patients with high disease burden was greater in the nafcillin group (54.8% vs. 39.1%; P = 0.011). Higher rates of in-hospital mortality were observed in the nafcillin group (15.1% vs. 6%; P = 0.016).

Conclusions: Our study observed significantly higher rates of clinical cure and reduced in-hospital mortality in patients who received cefazolin. Further analysis is warranted to evaluate the effectiveness of these agents and identifying predictors of treatment failure.

Keywords: Bacteremia; Cefazolin; MSSA; Nafcillin; Treatment.