Rapid Diagnostic Testing Decreases Broad Spectrum Antibiotic Use in Bloodstream Infections


A study showed utilizing a PCR-based test can narrow therapy quicker and help in resolving these infections sooner.

One of the more interesting emerging developments in medicine is the connection between rapid diagnostics and de-escalating antibiotics to enable optimal outcomes with quicker resolutions.

A group from the University of Pittsburgh Medical Center studied this clinical care scenario. Specifically, they conducted a retrospective, observational study comparing patients with Streptococcus spp bacteremia over two 6-month periods. The investigators utilized a pre-rapid diagnostic testing (RDT) time period and post-RDT time period. In the former, patients were prospectively followed by the antimicrobial stewardship program (ASP) and they provided recommendations based on gram-stain and organism identification results. During the latter, blood cultures were tested by GenMark ePlex BCID-GP that identifies S agalactiaeS anginosis group, S pneumoniaeS pyogenes and Streptococcus spp within 90 minutes which were reported directly to the ASP for recommendations on 3 actions: antibiotic discontinuation, de-escalation, or additional diagnostic testing.

What they found was that using rapid PCR testing had a positive effect on the timing of a broad-spectrum antibiotic course.

“With those results, we were able to narrow therapy sooner than we would with traditional identification methods,” said study investigator Tyler Tate, MD, fellow, University of Pittsburgh Medical Center.

“Our primary outcome was time to antibiotic de-escalation. In our pre intervention group, in which blood cultures were identified with traditional methods, our median time to de-escalation was approximately 8 hours. And in the post-intervention group, our median time to antibiotic de-escalation was approximately 42 hours with an average reduction of approximately 46 hours of time spent on broad spectrum therapy.”

Contagion spoke with Tate recently at IDWeek and he offered further insights on the study and how this form of testing can help with stewardship.


Tate T, Viehman A, Shields R. Rapid Diagnostic Testing is Associated with Decreased Broad Spectrum Antibiotic Use in Streptococcal Blood Stream Infections. Presented at: IDWeek 2023. October 11-14, 2023; Boston, MA. Abstract 94.

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