Rapid Diagnostic Testing’s Impact on Timing to Optimal Therapy


Utilizing a newer technology, investigators wanted to see if a reduction in time led to clinically significant antimicrobial adjustments.

Diagnostic stewardship is a newer concept in medicine. It has been defined as the appropriate use of laboratory testing to guide patient management, including treatment, in order to optimize clinical outcomes and limit the spread of antimicrobial resistance.1

One of the outgoing challenges in hospital medicine is the hours it can take to get from examination to diagnosis to optimal therapy. For example, when looking at blood samples, Saint Francis Hospital, Tulsa, Oklahoma had previously required a growth from a sub-culture of a positive blood culture prior to placing it on the Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF). In May of last year, the hospital incorporated the Sepsityper in-vitro diagnostic kit (IVD), which is designed to rapidly identify microorganisms directly.

As such, a team of investigators from St. Francis wanted to see if in using this rapid diagnostic technology, they could reduce time to optimal therapy. They performed a study with primary outcomes being time to appropriate (TTAT) and optimal antimicrobial therapy (TTOT). Their secondary outcomes included mortality, antimicrobial stewardship interventions, and hospital length of stay. The time to organism identification was also evaluated.

They included patients 18 years of age or older, who were admitted to Saint Francis Hospital and diagnosed with bacteremia.

“The time to organism identification was significantly shorter in the post-implementation phase at 32 hours compared to 46 hours in the pre-implementation phase (p< 0.01),” the investigators wrote. “Although our study found a significant reduction in time to organism identification by direct from specimen MALDI-TOF MS, this did not translate to clinically significant antimicrobial adjustments. Additional clinical resources, implementation of real-time positive blood culture alerts, and utilization of rapid diagnostic testing with resistance gene identification may result in more significant outcomes.”

The study, “Impact of a Rapid Diagnostic Test on Time to Acceptable and Optimal Antimicrobial Therapy,” was presented at the 24th Annual Making a Difference in Infectious Disease (MAD-ID) Meeting 2022 in Orlando, Florida from May 18-21.

Contagion spoke to lead author Alexander Aucoin, PharmD, BCPS, Saint Francis Hospital, at the MAD-ID meeting who provided further insights into the concept of diagnostic stewardship and his study’s findings.


1. Patel R, Fang FC. Diagnostic Stewardship: Opportunity for a Laboratory-Infectious Diseases Partnership. Clin Infect Dis. 2018 Aug 16;67(5):799-801. doi: 10.1093/cid/ciy077. PMID: 29547995; PMCID: PMC6093996.

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