Potential Microorganisms from Bronchial Lavage Fluid in Bronchiectasis Patients: Bacteria, Nontuberculous Mycobacteria, and Fungi.

Introduction: Bronchiectasis is a chronic lung disease characterized by irreversible bronchial dilation, often accompanied by persistent infections. Compared to sputum, the microbiological results of bronchial lavage fluid (BLF) from stable bronchiectasis patients are typically less explored. There is emerging evidence on the role of non-tuberculous mycobacteria (NTM) in the progression of bronchiectasis. This study aims to investigate the microbiological profiles of BLF and the rate of NTM detection in stable bronchiectasis patients.

Methods: We conducted a prospective observational multicenter study at two endoscopy units of Cho Ray's Hospital and University Medical Center Ho Chi Minh City, from January 2023 to January 2024. Adult patients with bronchiectasis who underwent bronchoscopy were enrolled, and the BLF was collected. The BLF samples were analyzed for bacterial and fungal pathogens using culture methods, and for NTM using the multiplex polymerase chain reaction (PCR) technique.

Results: Of the 112 initially assessed patients, 99 were eligible for this study. The mean age was 63 years, and 55.6% were female. Bacterial cultures were positive in 41.9% of cases (36/86), predominantly with isolates of Klebsiella pneumoniae and Pseudomonas aeruginosa. Multi-drug resistant (MDR) K. pneumoniae and Acinetobacter baumannii were notably detected. Using PCR, NTM was detected in 52.5% of patients (52/99), predominantly slow-growing species such as Mycobacterium xenopi and Mycobacterium avium-intracellulare complex. Fungal cultures were positive in 24.6% of cases (17/69), primarily involving Candida spp. and Aspergillus spp. Patients with higher bronchiectasis severity index had higher rates of positive bacterial culture, but lower rates of NTM detection.

Discussion: The high NTM detection rate in this study may be attributed to the use of BLF and sensitive molecular techniques. The frequent detection of NTM in patients with milder disease suggests that these organisms may be present in the early stages, potentially acting as an early warning for future progression. The high prevalence of MDR bacteria isolated highlights the need for revised infection control policies and tailored antibiotic strategies.

Conclusion: This study demonstrated a microbial diversity in BLF, notably NTM and MDR bacteria in Vietnamese patients with bronchiectasis, emphasizing the need for routine, comprehensive microbial assessment for bronchiectasis patients. The incorporation of advanced molecular techniques can improve the detection of NTM in these patients.