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Respiratory infections: what to expect from molecular tools?

Evaluation of a quantitative multiplex PCR panel for the diagnosis of pneumonia: how do we optimise utilisation?

May 18 • P4377

S. Whittier1, M. Lopez1, Y. Chen1

1) Columbia University Medical Center, New York, USA

Background: Guidelines for the management of adults with hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) were recently published by IDSA and ATS. For patients with suspected infections, the recommendations include empiric therapy against Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA). While antimicrobial de-escalation can occur when susceptibility results are available 48 hours after specimen collection, this is often a missed opportunity.

Materials/methods: We chose to evaluate a recently FDA-approved quantitative multiplex PCR panel designed to aid in the diagnosis of pneumonia in an effort to determine the potential impact on the recommendations of this guideline. A total of 126 BALs and mini-BALs submitted for routine bacteriologic culture were tested using the BIOFIRE® Pneumonia Panel (BioFire, Salt Lake City, UT), a multiplex PCR panel that includes 18 bacteria (15 of which are quantitated as copies/ml), 7 antimicrobial resistance markers and 8 viruses. BIOFIRE® Pneumonia Panel (PN Panel) results were compared to quantitative and semi-quantitative cultures. Out-patient (N = 29) and in-patient (N = 97) results were analyzed separately.

Results: Of the 97 in-patient specimens, 34 (35%) were categorized as positive (> 104 CFU/ml) for at least one bacterial pathogen by either PN Panel or culture. For 23 of these 34 (67%), PN Panel and culture were concordant. For discordants, 8/11 cultures grew organisms that are not on the PN Panel and 3/11 PN Panel were positive for PA and cultures were negative. PA and/or SA were detected in 15 of 34 (44%) positive samples. Sixty-three specimens were PN Panel negative and were ultimately finalized as “No growth” or “Mixed Commensal Microbiota”.

Conclusions: Based on this analysis, we determined that utilization of the PN Panel could have a positive impact on antimicrobial management of patients suspected to have HAP or VAP. Targeted therapy for patients with PA and/or SA could have been initiated for 44% and antimicrobial avoidance could have been considered for 65% of patients being evaluated. In conclusion, we believe the PN Panel is an excellent adjunct to other aspects of clinical care and diagnostic testing.

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Pneumonia Panel

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