A new novel test in practice: a clinical trial

In 2015 a paper, “Randomised Trial of Rapid Multiplex Polymerase Chain Reaction-Based Blood Culture Identification and Susceptibility Testing” by Banerjee et al, was published detailing the results of a clinical trial to assess the impact of a rapid diagnostic test (Multiplex, real-time PCR) applied to positive blood culture bottles. The trial included:

• a conventional blood culture work-up arm
• a new rapid test arm and
• the combination of the new rapid test and direct communication with the antimicrobial stewardship team.

The time to diagnosis was significantly decreased in the arms in which the new rapid test was used compared to the conventional arm.

However, streamlining was accomplished significantly sooner when rapid diagnostic testing was combined with the antimicrobial stewardship intervention.

The conclusion of the authors was:

“In this randomized trial, the BCID test reduced time to pathogen identification but only when BCID testing was combined with antimicrobial stewardship was time to appropriate antimicrobial de-escalation and escalation shortened. Rapid blood culture diagnostics should be implemented with antimicrobial stewardship”.

Accurate microbiological diagnosis does not always lead to appropriate antimicrobial prescribing. Knowledge (cognition) and action (behaviour) belong to different dimensions; this explains the know-do gap observed in this clinical trial.

Why modify antimicrobial therapy if the patient is having a favourable clinical course with broad-spectrum antimicrobials?

Why change an already winning team?

These are among the most frequently asked questions among prescribers when de-escalation is considered. Prescribers have to be motivated to de-escalate. The best way to motivate prescribers to streamline antimicrobial therapy is to educate them on the ecological benefits of targeted therapy assuring, on the other side, clinical efficacy.

As you will learn next week in Week 5 there are several barriers to prescribing changes (behaviour change) beyond the lack of knowledge.

Antimicrobial stewardship deals with them; it’s its modus operandi.