Does antibiotic administration sequence matter in bacteremia?

Reviewed by S. Shaefer Spires, MD, Duke Center for Antimicrobial Stewardship and Infection Prevention

In a multicenter, observational cohort of 3,376 patients with a bloodstream infection (BSI), administering the β-lactam agent prior to vancomycin was protective against 48-hour and 7-day mortality when they used inverse probability of treatment weighting incorporating propensity scores to account for selection bias.  This finding held true except for the cohort of patients with an MRSA BSI (<10%), in whom the order of antibiotics did not make a difference, supporting the conclusion of the authors prioritizing the β-lactam in empiric therapy when there is a concern for BSI.  This study is not without limitations, but these findings make sense when you consider the majority of BSIs in this country are Gram-negatives or Gram-positives sensitive to the β-lactams typically used in first line therapy for sepsis.  Therefore, the likelihood of adequately covering the pathogen sooner is higher when the β-lactam is given first or at least simultaneously, especially when treating patients with immunocompromising conditions in whom Gram-negative pathogens are more likely.


Amoah J, Klein EY, Chiotos K, Cosgrove SE, Tamma PD, for the CDC Prevention Epicenters Program. Administration of a β-lactam Prior to Vancomycin as the First Dose of Antibiotic Therapy Improves Survival in Patients with Bloodstream Infections. Clinical Infectious Diseases. 2021;(ciab865).

We use cookies to help improve your experience