Evaluation of the FilmArray® Pneumonia Plus Panel for Rapid Diagnosis of Hospital-Acquired Pneumonia in Intensive Care Unit Patients

Abstract

The FilmArray^® Pneumonia plus Panel (FAPP) is a new multiplex molecular test for hospital-acquired pneumonia (HAP), which can rapidly detect 18 bacteria, 9 viruses, and 7 resistance genes. We aimed to compare the diagnosis performance of FAPP with conventional testing in 100 intensive care unit (ICU) patients who required mechanical ventilation, with clinically suspected HAP. A total of 237 samples [76 bronchoalveolar lavages (BAL_DS) and 82 endotracheal aspirates (ETA_DS) obtained at HAP diagnosis, and 79 ETA obtained during follow-up (ETA_TT)], were analyzed independently by routine microbiology testing and FAPP. 58 patients had paired BAL_DS and ETA_DS. The positivity thresholds of semi-quantified bacteria were 10³-10⁴ CFUs/mL or 10⁴ copies/mL for BAL, and 10⁵ CFUs/mL or copies/mL for ETA. Respiratory commensals (H. influenzae, S. aureus, E. coli, S. pneumoniae) were the most common pathogens. Discordant results for bacterial identification were observed in 33/76 (43.4%) BAL_DS and 36/82 (43.9%) ETA_DS, and in most cases, FAPP identified one supplemental bacteria (23/33 BAL_DS and 21/36 ETA_DS). An absence of growth, or polybacterial cultures, explained almost equally the majority of the non-detections in culture. No linear relationship was observed between bin and CFUs/mL variables. Concordant results between paired BAL_DS and ETA_DS were obtained in 46/58 (79.3%) patients with FAPP. One of the 17 resistance genes detected with FAPP (mecA/C and MREJ) was not confirmed by conventional testing. Overall, FAPP enhanced the positivity rate of diagnostic testing, with increased recognition of coinfections. Implementing this strategy may allow clinicians to make more timely and informed decisions.

Keywords: antibiotic resistance; coinfection; hospital-acquired pneumonia; multiplex syndromic testing; rapid diagnosis.

FIGURE 1

Summary of FAPP and culture results. FAPP results distribution per pathogen category and sample type (A). Number of bacteria per sample with FAPP compared to culture in BAL_DS (B), ETA_DS (C), and ETA_TT (D). FAPP results compared to culture results for bacterial detection (E).

FIGURE 2

Comparison of 10⁴ and 10⁵ cutoffs with FAPP for ETA. Number of positive detections per sample for each threshold, in ETA collected at diagnosis (A) and 2–3 days later (B). Comparison of paired BAL_DS and ETA_DS for each threshold (C,D).

FIGURE 3

Analysis of discordant results between FAPP and culture at diagnosis, by rereading cultures in light of FAPP results, and by investigating the concordance with FAPP results from the paired ETA_DS/BAL_DS and/or ETA_TT if collected. Concordance and discordance between FAPP and culture identifications (A). Causes of discordant results in BAL_DS (B) and ETA_DS (C). Discrepancy investigations in BAL_DS (D) and ETA_DS (E).

FIGURE 4

Analysis of discordant results between FAPP and culture in ETA_TT. Causes of discordant results in ETA_TT (A). Discrepancy investigations for each additional bacteria detected by FAPP (B).