Abstract
BACKGROUND: The clinical impact of bacterial and mycobacterial isolates on bronchiectasis remains uncertain. METHODS: Patients with bronchiectasis at 16 hospitals in Taiwan were recruited with a 1-year follow-up. The patients were classified into six groups: Group 1, Pseudomonas aeruginosa; Group 2, Klebsiella pneumoniae; Group 3, other bacteria; Group 4, non-tuberculous mycobacteria (NTM); Group 5, daily sputum without bacterial or NTM colonisation; and Group 6, dry bronchiectasis. RESULTS: In total, 1416 patients (mean age 67 years; 43% males) were included. The mean modified Reiff score was 5 (range 1-18). 59% (829 patients) had sputum, whereas the remaining did not. The proportions of bacteria and NTM cultured from sputum within 1 year of observation were 27% (381/1416) and 15% (202/1416), respectively. The most common bacterial isolate was P. aeruginosa (13%), followed by K. pneumoniae (7%). 26% of the patients experienced severe exacerbations at least once within the year. The 1-year all-cause mortality rate was 3%. Patients with sputum exhibited a higher rate of severe exacerbations compared to patients with dry bronchiectasis, regardless of the presence of bacteria or NTM (p<0.001). Patients with bacterial colonisation had a higher mortality rate (p<0.001). Further, the highest mortality rate was observed among those with K. pneumoniae colonisation (hazard ratio (HR) 8.39 (95% CI 2.39-29.49)), followed by individuals colonised with other bacteria (HR 8.04 (95% CI 2.36-27.38)) and P. aeruginosa (HR 7.83 (95% CI 2.45-25.03)). Additionally, old age was an independent risk factor (HR 2.72 (95% CI 1.19-6.18)). CONCLUSION: K. pneumoniae was more frequently isolated from patients with bronchiectasis in Taiwan compared to Western countries and was associated with unfavourable clinical outcomes.