Clinical utility of rapid molecular diagnostics in acute exacerbation of bronchiectasis requiring hospitalisation: a prospective study

<bold>Background:</bold> Acute exacerbations of bronchiectasis (AEB) are key events in the natural course of disease. Microbiological workup by culture based method has long turnaround time and limited sensitivity. The clinical utility of rapid molecular diagnostics in AEB is unknown. <bold>Methods:</bold> This prospective observational study assessed the performance of BioFire FilmArray Pneumonia Panel (FA-PP) in adult patients admitted for AEB in an acute hospital in Hong Kong in 2022-2023. Spontaneous sputum samples were collected for bacterial culture and FA-PP on admission. Patients were followed up for recurrent AEB and mortality. <bold>Results:</bold> Of 77 patients admitted for AEB, FA-PP had a significantly higher bacterial detection rate compared to culture (79% vs 30%, p=0.003). FA-PP detected >2 bacteria in 29%, and virus in 23% of patients. FA-PP had a sensitivity of 100% for all cultured bacteria. Pseudomonas aeruginosa was the most common bacteria detected using both methods (FA-PP: 43%, culture: 26%). When compared with culture, the sensitivity, specificity, positive and negative predictive values of FA-PP for Pseudomonas aeruginosa were 100%, 77%, 61% and 100%, respectively. FA-PP positivity for Pseudomonas aeruginosa was associated with increased risk of recurrent AEB (HR 2.67, 95%CI [1.30-5.48], p=0.008), but similar mortality risk (HR 1.84, 95%CI [0.73-4.67], p=0.198). <bold>Conclusion:</bold> FA-PP is highly sensitive in detecting respiratory pathogens in patients hospitalised for AEB. Pseudomonas aeruginosa is the most common pathogen detected by both culture and rapid molecular methods. FA-PP positivity for Pseudomonas aeruginosa is associated with higher risk of recurrent AEB.