Methicillin-resistant Staphylococcus Aureus Sterile-site Infection: The Importance of Appropriate Initial Antimicrobial Treatment

Objective: The first goal of this investigation was to determine the rate of appropriate initial antimicrobial administration to patients with methicillin-resistant Staphylococcus aureus (MRSA) sterile-site infections. Our second goal was to evaluate the influence of appropriate initial treatment of MRSA sterile-site infection on outcome.

Design: A retrospective, single-center, observational cohort study.

Setting: Barnes-Jewish Hospital, a 1200-bed urban teaching facility.

Patients: Adult patients requiring hospitalization identified to have an MRSA sterile-site infection.

Interventions: Retrospective data collection from automated hospital and pharmacy databases.

Measurements And Main Results: Five hundred forty-nine patients with S. aureus sterile site infections were identified during a 3-yr period (January 2002 through December 2004). One hundred twenty-seven (23.1%) died during hospitalization. Hospital mortality was statistically greater for patients receiving inappropriate initial antimicrobial treatment (n = 380) within 24 hrs of a positive culture than for those receiving appropriate initial treatment (n = 169) (26.1% vs. 16.6%; p = .015). Multiple logistic regression analysis identified inappropriate initial antimicrobial treatment (adjusted odds ratio [AOR], 1.92; 95% confidence interval [CI], 1.48-2.50; p = .0134), vasopressor administration (AOR, 5.49; 95% CI, 4.08-7.38; p < .001), and increasing age (1-yr increments) (AOR, 1.03; 95% CI, 1.02-1.04; p < .001) as independent determinants of hospital mortality.

Conclusions: Inappropriate initial antimicrobial treatment of MRSA sterile-site infections is common and is associated with an increased risk of hospital mortality. Appropriate antimicrobial treatment of MRSA sterile-site infections may be maximized by increased use of initial empirical antimicrobial treatment regimens targeting MRSA in patients at risk for this infection until organism identification and susceptibility become known.