Abstract:

Objective: This study aims to offer critical insights into the prevention and treatment of non-tuberculous mycobacterial pulmonary disease (NTM-PD) by analyzing the isolation rates and drug resistance patterns of respiratory non-tuberculous mycobacteria (NTM) in the Wuhan area, as well as the clinical characteristics of patients diagnosed with NTM-PD. Methods: This retrospective study encompassed 8619 hospitalized patients with suspected mycobacterial pulmonary infections at Wuhan Pulmonary Hospital from March 2021 to October 2023. All participants were aged 15 years or older, and their respiratory samples (including sputum, induced sputum, and bronchiolar lavage fluid) tested positive for mycobacterial etiology (via mycobacterium culture) and were identified as NTM. Comprehensive data on medical history, clinical features, radiological findings, clinical diagnosis, and treatment were collected for all subjects. The isolation rates, demographic characteristics, and drug resistance profiles of NTM strains were analyzed. Patients diagnosed with NTM-PD were categorized into three groups based on the infecting species: M.intracellular (M.intracellular group), M.abscessus (M.abscessus group), and M.kansasii (M.kansasii group). The baseline characteristics, clinical symptoms, radiological features, underlying diseases, and concomitant pulmonary conditions of each group were compared. Results: Among the 8619 subjects, 629 clinical isolates were identified as NTM strains, resulting in an NTM isolation rate of 7.30%. A total of 653 NTM strains were isolated, comprising 398 (60.95%) strains of M.intracellular, 138 (21.13%) strains of M.abscessus, 41 (6.28%) strains of M.avium, and 41 (6.28%) strains of M.kansasii. Among the 510 patients diagnosed with NTM-PD, 297 (58.24%) were female. The primary clinical symptoms included cough (71.96%, 367/510), expectoration (51.76%, 264/510), and hemoptysis (26.67%, 136/510). Key radiological features were patchy infiltrates (61.57%, 314/510), nodules (65.49%, 334/510), bronchiectasis (79.02%, 403/510), and cavities (40.98%, 209/510). The most common underlying conditions were anemia (24.12%, 123/510) and hypoproteinemia (24.90%, 127/510). Pulmonary diseases were predominantly associated with emphysema bullosa (18.63%, 95/510) and chronic obstructive pulmonary disease (17.84%, 91/510). The study categorized NTM-PD patients into three groups: 332 cases in the M.intracellular group, 115 cases in the M.abscessus group, and 35 cases in the M.kansasii group. The proportion of females was 55.12% (183/332) in the M.intracellular group, 75.65% (87/115) in the M.abscessus group, and 17.14% (6/35) in the M.kansasii group, with a statistically significant difference (χ²=39.534, P<0.001). The mean ages were (63.60±10.67) years for the M.intracellular group, (60.60±10.26) years for the M.abscessus group, and (53.30±13.20) years for the M.kansasii group, also showing a statistically significant difference (F=15.724, P<0.001). Significant differences were observed in the proportions of smokers (23.19% (77/332), 12.17% (14/115), 42.86% (15/35); χ²=15.623, P<0.001) and alcohol users (10.54% (35/332), 4.35% (5/115), 22.86% (8/35); χ²=10.079, P=0.006) across the groups. Additionally, the incidence of bronchiectasis (78.31% (260/332), 90.43% (104/115), 54.29% (19/35); χ²=22.345, P<0.001) and cavity formation (42.77% (142/332), 29.57% (34/115), 68.57% (24/35); χ²=17.534, P<0.001) varied significantly among the M.intracellular, M.abscessus, and M.kansasii groups. There were statistically significant differences in the incidence of chronic obstructive pulmonary disease (COPD)(18.67% (62/332), 15.65% (18/115), 37.14% (13/35); χ²=8.222, P=0.016) and pulmonary aspergillosis (6.93% (23/332), 1.74% (2/115), 11.43% (4/35); χ²=7.016, P=0.030) among the M.intracellular, M.abscessus, and M.kansasii groups. The resistance rates of M.avium and M.intracellular to clarithromycin, amikacin, and linezolid were 0, 0, and 23.53% (4/17) for M.avium, and 3.14% (5/159), 6.92% (11/159), and 13.21% (21/159) for M.intracellular, respectively. The resistance rate of M.kansasii to clarithromycin, amikacin, linezolid, moxifloxacin, rifampin, and rifabutin was 0, while the resistance rate to ciprofloxacin was 43.75% (7/16). The resistance rates of M.abscessus to clarithromycin, amikacin, linezolid, and cefoxitin were 7.02% (4/57), 1.75% (1/57), 43.86% (25/57), and 8.77% (5/57), respectively. Conclusion: The predominant NTM strains isolated from the respiratory tracts of hospitalized patients with suspected mycobacterial pulmonary infection in the Wuhan area were M.intracellular, M.abscessus, and M.kansasii. Except for M.kansasii, other NTM strains exhibited higher resistance to common antituberculosis drugs. There were notable differences in sex distribution, radiological features, and associated pulmonary diseases among patients with M.intracellular pulmonary disease, M.abscessus pulmonary disease, and M.kansasii pulmonary disease.

Key words: Atypical bacteria, Mycobacterium, Bacterial drug resistance, Disease characteristics