Rapid Testing Cuts Time to Appropriate Antibiotics in ICU Pneumonia

Rapid molecular pathogen testing could substantially accelerate appropriate antibiotic treatment for critically ill patients with suspected pneumonia, according to findings from the IRISPAT-1 randomised controlled feasibility trial.

The study evaluated whether multiplex polymerase chain reaction (mPCR) testing could improve antimicrobial decision-making in mechanically ventilated adults with suspected pneumonia. Although molecular panels can rapidly identify respiratory pathogens, evidence supporting their impact on antimicrobial therapy in critical care remains limited.

Researchers enrolled 40 mechanically ventilated patients with suspected pneumonia between July 2024 and October 2025. All participants had started new antibiotic treatment within 24 hours and were randomly assigned to receive either standard care or testing with the BioFire FilmArray Pneumonia Panel alongside standard care.

The primary outcome was the time taken for patients to receive appropriate antimicrobial therapy.

Appropriate Treatment Reached 65 Hours Earlier

Patients undergoing rapid mPCR testing received appropriate antibiotic therapy considerably sooner than those receiving standard care.

Median time to appropriate treatment was 7 hours in the mPCR group, compared with 72 hours in the standard-care group. This represented a statistically significant difference, with patients in the rapid-testing group more than three times as likely to reach appropriate antimicrobial therapy sooner than controls (HR: 3.3; 95% CI: 1.6–6.6; p=0.001).

Importantly, clinicians demonstrated high adherence to the accompanying antibiotic treatment algorithm. Recommendations were followed in 18 of the 20 patients, corresponding to an adherence rate of 90%.

The results suggest that combining rapid pathogen identification with a structured antimicrobial treatment algorithm may help clinicians make targeted treatment decisions considerably earlier than conventional diagnostic approaches.

No Reduction in Broad-Spectrum Antibiotic Use

Despite the substantial improvement in time to appropriate treatment, rapid testing did not significantly affect several other antimicrobial or clinical outcomes.

Researchers found no difference between groups in the use of broad-spectrum antibiotics or overall duration of antibiotic treatment. Similarly, ventilator-free days, vasopressor-free days, and 28-day mortality did not differ between the two treatment strategies.

These findings are important when interpreting the potential clinical impact of the intervention. While rapid testing accelerated appropriate antimicrobial selection, the small feasibility trial was not able to demonstrate that this translated into improved patient outcomes or reduced overall antibiotic exposure.

Larger Trials Needed to Establish Clinical Impact

Rapid identification of pathogens could be particularly valuable in intensive care, where clinicians often need to begin empirical broad-spectrum antimicrobial therapy before conventional microbiological results become available.

The IRISPAT-1 findings provide preliminary evidence that mPCR testing can substantially shorten the time required to reach appropriate therapy when incorporated into a structured antibiotic management approach.

However, with only 40 participants from a single centre, the results require confirmation in larger studies. Further research will be needed to determine whether faster antimicrobial optimisation can reduce unnecessary broad-spectrum antibiotic exposure, improve antimicrobial stewardship, or ultimately translate into better clinical outcomes for critically ill patients with pneumonia.

Reference

Lai CK et al. Impact of rapid pathogen detection in ICU patients with suspected pneumonia on antimicrobial therapy: randomized, controlled open-label feasibility trial (IRISPAT-1). BMC Pulm Med. 2026;DOI:10.1186/s12890-026-04596-2.