Distribution of species of non-tuberculous Mycobacteria in bronchoalveolar lavage fluid of patients with suspected pulmonary tuberculosis and resistance to anti-tuberculosis drugs

OBJECTIVE To investigate the distribution of non-tuberculous Mycobacteria (NTM) in bronchoalveolar lavage fluid (BALF) of patients with suspected pulmonary tuberculosis and analyze the resistance to anti-tuberculosis drugs. METHODS A total of 140 patients with suspected pulmonary tuberculosis who were treated in Zhoushan Hospital from Aug 2020 to Oct 2022 were recruited as the research subjects, 58 of whom were diagnosed with NTM pulmonary disease ( the NTM pulmonary disease group) , and 82 were diagnosed with pulmonary tuberculosis ( the pulmonary tuberculosis group ). The clinical characteristics of NTM pulmonary disease, distribution of the species and drug resistance were summarized. RESULTS The proportion of patients with previous bronchiectasis was higher in the NTM pulmonary disease group than in the pulmonary tuberculosis group (P＜0.05); the percentage of neutrophils of the NTM pulmonary disease group was lower than that of the pulmonary tuberculosis group, while the albumin level and the proportion of patients with bronchiectasis shadow were higher in the NTM pulmonary disease group than in the pulmonary tuberculosis group(P＜0.05). Totally 39 (67.24%) strains of slow-growth pathogens were isolated from BALF specimens of the NTM pulmonary disease group, 22 of which were Mycobacterium intracellulare; 19 (32.76%) strains of fast-growth pathogens were isolated, 18 of which were Mycobacterium chelonae/abscessus. As the major species of pathogens leading to NTM pulmonary disease, the drug resistance rate of M.intracellulare to clofazimine, and the drug resistance rates to isoniazid, rifampicin, streptomycin, ethambutol, levofloxacin, amikacin, capreomycin, aminosalicylic acid, kanamycin and linezolid were more than 70.00%; the drug resistance rates of the M.chelonae/abscessus to isoniazid, rifampicin, streptomycin and aminosalicylic acid were 100.00%, and the drug resistance rates to the rest of 8 types of antibiotics were more than 80.00%. CONCLUSION There are no specific clinical characteristics about the NTM pulmonary disease. M.intracellulare and M.chelonae/abscessus are the predominant species of pathogens and are highly resistant to the commonly used anti-tuberculosis drugs.