ABSTRACT
Objective@#To determine the clinical significance of nontuberculous mycobacteria (NTM) isolated from respiratory specimens. @*Methods@#Clinical data of patients with NTM strains isolated from the respiratory tract between January 2014 and February 2017 were retrospectively analyzed. Clinical significance of NTM isolated strains was evaluated based on diagnostic criteria of NTM pulmonary diseases from American Thoracic Society (ATS). Quantitative data of two groups were analyzed by independent t test. Categorical data were analyzed by Pearson χ2 test or Fisher exact test. @*Results@#Totally 352 NTM strains from 257 patients had been isolated between January 2014 and February 2017. Among 15 identified NTM species, M. intracellular (51.7%, 182/352), M. abscessus (25.6%, 90/352), and M. avium (10.8%, 38/352) were predominant. Of the 157 patients with full clinical data involved in the analysis, 58 (36.9%) patients were determined to have definite disease, and 34 patients (21.7%) were designated as probable disease candidates, and 16 (10.2%) patients were regarded as uncertain disease, and 49(31.2%) patients were diagnosed as unlikely disease. The age of 58 patients with definite disease was (63.9±12.7) years, and 48.3% (28/58) were female. M. intracellulare (55.2%, 32/58) was the main cause of pulmonary NTM disease, followed by M. abscessus (25.9%, 15/58) and M. avium (12.1%, 7/58), while other NTM species only accounted for 6.8% (4/58). Definite cases with M. intracellulare, M. abscessus, M. avium, M. kansasii, M. marseillense, and M. columbia accounted for 35.2% (32/91), 57.7% (15/26), 7/15, 2/3, 1/3 and 1/2, respectively, among patients with corresponding isolations, while patients with other species of isolation did not meet the diagnostic criteria. Patients with clinical significant isolation of NTM were older than those without clinical significance (χ2=3.603, P=0.000), and proportion of anti-acid staining positivity of patients with clinical significance was higher than that of patients without clinical significance (χ2=18.815, P=0.000). The proportion of M. abscessus in patients with clinical significance was higher than that in patients without clinical significance (χ2=6.313, P=0.012). However, there was no significant difference between the two groups in the isolation of M. Gordon (Fisher exact test, P=0.028). The proportion of M. abscessus lung disease in women was 11/15, which was higher than that of M. intracellulare lung disease (41.5%, 17/41), and the difference between the two groups was statistically significant (χ2=4.462, P=0.035). There was no significant difference of clinical symptoms and underlying diseases in NTM lung disease among different groups (all P>0.05). In these patients with definite disease, 39.7% (23/58) of them manifested the upper lobe cavitary form, 53.4% (31/58) exhibited nodular bronchiectatic form, and only 6.9% (4/58) exhibited unclassified form. The upper lobe cavitary form (43.8%, 14/32) and the nodular bronchiectatic form (53.1%, 17/32) dominated in patients with M. intracellulare lung disease. M. abscessus lung disease was dominated by the nodular bronchiectatic form (11/15) while the upper lobe cavitary form only accounts for 3/15. There was no significant difference of image characteristics between NTM lung disease and other different groups (all P>0.05). @*Conclusions@#36.9% of the patients with NTM isolates met the ATS diagnostic criteria for NTM lung disease. Different species have different clinical significance. M. intracellulare and M. abscessus are the most predominant NTM isolated species that cause NTM lung disease. Majority of patients manifest as the upper lobe cavitary form, followed by the nodular bronchiectatic form.
ABSTRACT
Objective To investigate the isolation rate, distribution and trend of nontuberculous mycobacteria (NTM) in Wenzhou during 2014 to 2016.Methods Sputum or alveolar lavage specimens of patients with suspected pulmonary tuberculosis were collected for mycobacteria culture from January 2014 to December 2016.Mycobacterium culture positive strains were further identified by gene chip, 16S rRNA and hsp65 gene sequencing.SPSS 19.0 software was used to analyze the data.Results After excluding repetitive strains, 3 295 mycobacteria strains (MTB) were isolated from respiratory specimens, included 3 032 mycobacterium tuberculosis complex strains, 238 NTM strains, 20 Gordon genera strains, 3 Nocardia genera strains and 2 Tsukamurella genera strains.The proportion of NTM among confirmed mycobacteria was 8.5％ (86/1 006), 6.7％ (72/1 079) and 6.8％ (80/1 185) in 2014, 2015 and 2016, respectively (x2 =2.459,P ＞ 0.05).The overall prevalence of NTM was 7.3 ％ (238/3 270).There were 15 species of NTM, and the most common NTM strain was Mycobacterium intracellulare (52.5％,125/238), followed by Mycobacterium abscessus (22.7％, 54/238) and Mycobacterium avium (10.1％, 24/238), other species were only accounted for 14.7％ (35/238).The ranking of Mycobacterium avium went up rapidly from the fifth in 2014 to the second in 2016 (x2 =18.259, P ＜ 0.01), while proportion of Mycobacterium abscess, dropped from 34.9％ (30/86) in 2014 to 17.5％ (14/80) in 2016 (x2 =7.335, P＜0.01).Among patients from whom the NTM strains were isolated, 56.7％ (135/238) were male and most of them were aged 45 years or above (79.8％, 190/238).Conclusions In the past three years, the trend of NTM isolation rate in Wenzhou is steady.The most prevalent NTM species is Mycobacterium intracellulare, followed by Mycobacterium abscessus and Mycobacterium avium.Mycobacterium avium shows a continuously upward trend, while the separation of Mycobacterium abscessus shows a downward trend.