Clinical characteristics and drug susceptibility test of nontuberculous mycobacterial lung disease

Objective: To investigate the clinical characteristics and drug susceptibility test (DST) of patients infected with different nontuberculous mycobacteria (NTM). Methods: The patients with nontuberculous mycobacterial lung disease (NMLD) in Shanghai Pulmonary Hospital from March 2014 to March 2015 were studied retrospectively by analyzing the clinical characteristics, radiological features and DST results. A total of 201 NMLD patients [male 108, age(58+/-15) yrs] were enrolled into this study including 48 cases of M. Kansasii [male 13, age (52+/-16) yrs],46 cases of M. Abscess[male 46, age (57+/-16) yrs], 92 cases of M. Intracellulare [male 43, age (61+/-13) yrs], and 15 cases of M. Avium [male 6, age (67+/-10) yrs]. Clinical data were collected when the diagnosis was made and Chi-square test was used to compare the differences among 4 groups of patients. Bonferroni method was used for further pairwise comparisons. Results: There were significant differences among the 4 groups in the age(chi(2)=6.42, P<0.001) and the gender(chi(2)=49.18, P<0.001) of the patients. The history of bronchiectasis in the groups of M. Kansasii, M. Abscess, M. Intracellulare and M. Avium were 2/48, 31/46, 39/92 and 4/15 cases respectively(chi(2)=41.84, P<0.001). For the Gamma-interferon release assays (ELISA) (IGRA), the positive rate of IGRA in the groups of M. Kansasii, M. Abscess, M. Intracellulare and M. Avium were 83%(40/48), 30%(14/46), 23%(21/92) and 33% (5/15) respectively(chi(2)=50.96, P<0.001). The radiological features were significantly different in tree-in-bud(8/48, 35/46, 36/92 and 4/15 cases respectively, chi(2)=36.48, P<0.001), pleural thickness or mild effusion (21/48, 36/46, 69/92 and 7/15 cases, chi(2)=19.54, P<0.001), bronchiectasis (20/48, 39/46, 78/92 and 10/15 cases, P<0.001) and cavities (38/48, 21/46, 63/92 and 10/15 cases, chi(2)=12.38, P<0.001) among the 4 groups(M. Kansasii, M. Abscess, M. Intracellulare and M. Avium). The drug resistance rates of M. Kansasii to rifampin, ethambutanol and ofloxacin were 10%(5/48), 8%(4/48) and 15%(7/48) respectively; the resistance rates of M.Intracellulare to ethambutanol was 45%(41/92), and the resistance rates of M.Abscess were all over 80% to all anti-TB drugs. The results of pairwise comparisons showed that the male proportion(46/48) and IGRAs positive rate(40/48) of patients with M. Kansasii were higher than those of other groups, and the incidence of bronchiectasis(20/48) and pleural changes(21/48) was lower than those of other groups. The female ratio(33/46), history of bronchiectasis (31/46) and tree-in-bud sign of patients(35/46) with M. Abscess were higher than those of other groups. Conclusions: There were differences in the clinical manifestations and imaging features of 4 common NMLD diseases, which were helpful for clinical differentiation. The patients with M. Kansasii infection were mainly male, with a high IGRA positive rate and fewer lesions of bronchiectasis or pleural changes. Most of the patients with M. Abscess were female, with a previous history of bronchiectasis, and with most of the lesions showing tree-in-bud signs. The NTM species had a high rate of resistance to anti-TB drugs except M. Kansasii.