Prospective Multicenter Evaluation of a multiplex PCR Pneumonia Panel to Distinguish Infectious Pneumonia from Non-Infectious Mimics in ICU Respiratory Failure.

BackgroundInfective pneumonia is a major cause of respiratory failure and ICU admission, but non-infectious mimics-such as autoimmune disease, malignancy, and organizing pneumonia-are also common. Multiplex PCR pneumonia panels may help differentiate these entities.MethodsWe conducted a prospective before-and-after study (1 Jan 2024-30 Jun 2025) evaluating the FilmArray Pneumonia plus panel (FAPN) in adults with respiratory failure admitted to two district general hospital ICUs. Consecutive patients undergoing FAPN testing (n = 116) were included. In the post-intervention cohort (n = 56), a consensus panel determined the cause of respiratory failure in patients with suspected pneumonia (PF ratio <300 mm Hg and ≥1 radiographic quadrant involvement). Agreement between FAPN and sputum culture-including the diagnostic value of a negative FAPN-was assessed.ResultsAmong post-intervention patients with suspected pneumonia (n = 45), the combined finding of "negative FAPN and negative sputum culture" identified non-infectious mimics with a sensitivity of 75% (95% CI 50-100%) and specificity of 91% (95% CI 81-100%). In multivariable analysis, negative FAPN results were associated with reduced antibiotic escalation (OR 0.70; p < .01). The positive predictive value of individual FAPN bacterial targets ranged from 0%-100% (median 35%). Culture confirmation increased with higher FAPN quantitative bins: 8% at 104 CFU/mL, 7% at 105 CFU/mL, 48% at 106 CFU/mL, and 57% at 107 CFU/mL.ConclusionsIn ICU patients with suspected pneumonia, a combined negative FAPN and sputum culture result should prompt evaluation for non-infectious mimics. Negative FAPN findings may help reduce unnecessary antibiotic escalation, although their positive predictive value for culture-confirmed bacterial infection is limited.