Frequency and relevance of nontuberculous mycobacterial isolates in patients with COPD exacerbations

<bold>Introduction:</bold> Chronic obstructive pulmonary disease (COPD) is a known risk factor for nontuberculous mycobacterial pulmonary disease (NTM-PD), and inhaled corticosteroid (ICS) therapy has also been associated with an increased incidence of NTM-PD. However, there is limited information on the yield of NTM screening in COPD patients. <bold>Aim:</bold> The aim of our study was to determine the frequency and relevance of NTM isolates in patients with COPD exacerbations at the University Hospital Centre Zagreb. <bold>Methods:</bold> a retrospective analysis of mycobacterial cultures obtained from COPD patients during exacerbations between January 1st, 2021 and December 31st, 2022. Both sputum and bronchoscopy obtained samples were included in the analysis. <bold>Results:</bold> Our cohort encompassed 175 COPD patients (GOLD I 3.4%, GOLD II 19.4%, GOLD III 32.1%, GOLD IV 29.7%, unknown 15.4%; frequent exacerbators 50.28%, unknown 1.7%; ICS therapy in 63.4%). NTM were isolated from 5/175 (2.86%) of patients: 4 <italic>M. avium</italic> and 1 <italic>M. xenopi</italic>. The NTM group didn’t differ from the non-NTM group in average age (66.3 vs. 69.85), average smoking pack-years (57 vs. 53), or mean BMI (25.14 vs. 25.32 kg/m²). However, all patients with NTM isolate were frequent exacerbators and used ICS but, interestingly, had only moderate severity of obstruction in spirometry. Only two out of five patients had NTM-PD, both caused by <italic>M. avium</italic>. <bold>Conclusion:</bold> In our setting, the yield of NTM screening in COPD exacerbations is low and might be recommended only in COPD patients with a phenotype of frequent exacerbator and ICS therapy, regardless of the obstruction severity.