A variety of bacterial aetiologies in the lower respiratory tract at patients with endobronchial tuberculosis

Recently, our understanding of the elusive bacterial communities in the lower respiratory tract and their role in chronic lung disease has increased significantly. However, little is known about the respiratory microorganisms in patients with endobronchial tuberculosis (EBTB), which is a chronic inflammatory disease characterized by destruction of the tracheobronchial tree due to Mycobacterium tuberculosis (MTB) infection. We retrospectively reviewed data for histopathologically and microbiologically confirmed EBTB patients diagnosed at a tertiary referral hospital in South Korea between January 2013 and January 2019. Bacterial cultures were performed on bronchial washing from these patients at the time of EBTB diagnosis. A total of 216 patients with EBTB were included in the study. The median age was 73 years and 142 (65.7%) patients were female. Bacteria were detected in 42 (19.4%) patients. Additionally, bacterial co-infection was present in 6 (2.8%) patients. Apart from MTB, the most common microorganisms identified were Staphylococcus aureus (n = 14, 33.3%) followed by Klebsiella species (n = 12, 28.6%; 10 Klebsiella pneumoniae, 2 Klebsiella oxytoca), Streptococcus species (n = 5, 11.9%), Enterobacter species (n = 4, 9.5%), and Pseudomonas aeruginosa (n = 3, 7.1%). A variety of microorganisms were isolated from the bronchial washing indicating that changes in microorganism composition occur in the airways of patients with EBTB. Further studies are needed to investigate the clinical significance of this finding.