Evaluation of rapid multiplex PCR for investigation of lung microbiology in bronchiectasis – preliminary data from the BRILLIANT study

<bold>Introduction:</bold> Sputum is frequently used to study infection in bronchiectasis patients, however there are few studies on the relationship between sputum and bronchoalveolar lavage (BAL) microbiology. Molecular diagnostics have demonstrated greater sensitivity than traditional culture; this has not been extensively tested in bronchiectasis. <bold>Methods:</bold> The BRILLIANT study is an observational cohort study in which clinically stable HRCT-confirmed bronchiectasis patients and healthy controls undergo bronchoscopy and BAL sampling; patients also provide a sputum sample if able. BAL and sputum are analysed on the BioFire® FilmArray® Pneumonia (PN) Panel; BAL samples also undergo traditional culture and microscopy. <bold>Results:</bold> 46 patients (age 70 (59.5-75.8), 52% female, BSI 5 (4-7)) and 10 healthy volunteers (age 41.5 (37-53.8), 80% female) have provided samples to date. BioFire detected pathogens, both viral and bacterial, in 25/46 patients (54.3%). Culture conversely identified bacteria in 17/46 patients (37%). Common pathogens identified by PCR and culture respectively include <italic>Haemophilus influenzae</italic> (23.9% vs 17.4%), <italic>Pseudomonas aeruginosa</italic> (10.9% vs 6.5%), <italic>Staphylococcus aureus</italic> (10.9% vs 4.3%), and <italic>Escherichia coli</italic> (6.5% vs 4.3%). Viruses were detected in 8.7% of patients and 20% of controls. <bold>Conclusion:</bold> Although limited by sample availability, BAL and sputum BioFire results were generally concordant. Rapid multiplex PCR is more sensitive than culture for identifying bacterial targets, plus viral targets. Sputum appears to be an acceptable substitute for BAL microbiology results.