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Respiratory infections: what to expect from molecular tools?

Microbiological Point-of-Care analysis of endotracheal aspirate from intubated patients admitted to the intensive care unit

April 21 • P4386

DØ. Christensen1/2, D.K. Kur3, J. Brandt1/2, M. Hindborg1/2, C. D. Sørensen1, M. Kolpen4, C. Jensen3, F.B. Hertz5, J. Bangsborg5, M.H. Bestle1/2

1) Northzealands Hospital - Hillerød, Dept. of Anaestesiology and Intensive Care, Hillerød, Denmark
2) Copenhagen University, Dept. of Clinical Medicine, København, Denmark
3) Northzealands Hospital - Hillerød, Dept. of Clinical Biochemistry, Hillerød, Denmark
4) Rigshospitalet, Dept. of Clinical Microbiology, København, Denmark
5) Herlev Hospital, Dept. of Clinical Microbiology, Herlev, Denmark

Background: The paraclinical diagnosis of lower respiratory tract infection(LRTI) still relies heavily on culturing of respiratory tract samples, which are quite insensitive, hence resulting in false negative response. There is a growing market for commercially available multiplex polymerase chain reaction (PCR) assays promising fast turnaround time (TAT) and high sensitivity towards a variety of common pathogens, which may improve antibiotic stewardship. The purpose of this study was to assess the applicability of the BIOFIRE® FILMARRAY® Pneumonia plus Panel (PNplus Panel) in the clinical setting of an Intensive Care Unit (ICU).

Materials/methods: Tests were performed on undiluted specimens from mechanically ventilated patients at the ICU on the first day of intubation. The BIOFIRE® FILMARRAY® Pneumonia plus Panel was used to test 76 endotracheal aspirate samples frozen in a biobank. Comparison with pathogen detection using conventional microbiological methods (CMM) was performed, and concordance rates between methods was assessed taking into account incomplete investigation by conventional methods. Evaluation on the usage of antibiotics was done retrospectively by a clinical microbiologist and an Intensive Care physician assessing a potential change in treatment based on BIOFIRE® results and patient status.

Results: In 42 (55.3%) samples PNplus Panel and CMM are in full concordance. Additional findings by CMM were seen in 2 (2.6%) samples. Additional findings by PNplus Panel were seen in 31 (40.7%) samples. Complete discrepancy between methods were seen in 1 (1.3%) sample. In 2 samples, PNplus Panel detected methicillin resistant Staphylococcus aureus, even though CMM showed methicillin sensitive Staphylococcus aureus. By CMM, extended virus panel TAT was a median of 111,28h. TAT for culture and susceptibility a median 52,82h. PCR for atypical 40,04h. PNplus Panel TAT was estimated 2h, making de-escalation possible in 35 (46.1%) patients, among these discontinuation of macrolide would have been possible in 24 (31.6%).

Conclusions: The BIOFIRE® FILMARRAY® Pneumonia plus Panel may offer valuable information, however it detected several additional pathogens compared to conventional microbiological methods and the interpretation of results appears difficult in terms of disease causality and antibiotic resistance. The biggest impact may be on fast-delivered negative results, which resonated in the possible discontinuation of macrolide. Even though our study showed potential for the BIOFIRE® FILMARRAY® Pneumonia plus Panel, further investigations on clinical effect should be performed prospectively.

filmarray

Pneumonia Panel

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