Background: Tuberculosis (TB) is a major infectious disease worldwide; there has been a significant increase in the number of elderly patients with TB, largely contributing to TB-related mortality. Although endobronchial tuberculosis (EBTB) is a unique form of pulmonary TB, available data on the clinical characteristics and drug susceptibility (DST) patterns of patients with EBTB are scarce.
Methods: We evaluated the clinical characteristics of patients with EBTB in South Korea and the culture-based DST patterns of EBTB. Further, the DST patterns were compared between elderly (≥65 years) and young (<65 years) patients. We retrospectively reviewed data of patients with EBTB who had the results of DST and were diagnosed between January 2013 and December 2019 at a tertiary referral hospital in South Korea. Phenotypic DST of 15 first-line and second-line anti-TB drugs was performed using Mycobacterium tuberculosis isolates prior to treatment.
Results: Of the 230 patients with EBTB, 69% were in elderly patients (≥65 years). Any-resistance occurred in 24 patients (10.4%), while multi-drug resistance (MDR) and extensive drug resistance (XDR) were observed in six patients (2.6%). Compared to that of the elderly treatment-naïve patients, previously treated elderly patients had a significantly higher proportion of resistance to rifampin (14.3% vs. 2.2%; P=0.031), ethambutol (9.5% vs. 0.7%; P=0.046), and pyrazinamide (9.5% vs. 0.7%; P=0.046). Further, MDR/XDR was observed more frequently in the previously treated elderly patients than that in the treatment-naïve elderly patients (14.3% vs. 1.4%; P=0.017). A relatively small number of drug-resistant cases (5.6%) were observed in young patients.
Conclusions: Elderly EBTB patients with previous Anti-tuberculous medications had a significantly higher proportion of drug-resistant TB. These patients should be carefully assessed using DST analysis before treatment.
Keywords: Bronchoscopy; drug resistance; endobronchial tuberculosis (EBTB); microbial sensitivity tests.