Abstract
Pulmonary diseases caused by nontuberculous mycobacteria (NTM) are increasing in incidence and prevalence worldwide. In this study, we identified NTM species of the clinical isolates from 8 provinces in China, in order to preliminarily provide some basic scientific data in the different species and distribution of NTM related to pulmonary disease in China. A total of 523 clinical isolates from patients with tuberculosis (TB) diagnosed clinically from 2005 to 2012 were identified to the species using conventional and molecular methods, including multilocus PCR, rpoB and hsp65 PCR-PRA, hsp65, rpoB, and 16S-23S internal transcribed spacer region sequencing. The isolates were identified into 3 bacterium genera, including NTM, Gordonia bronchialis, and Nocardia farcinica, and, for the 488 NTM isolates, 27 species were identified. For all the 27 species of NTM which were found to cause pulmonary infections in humans, the most prevalent species was M. intracellulare, followed by M. avium and M. abscessus. And seven other species were for the first time identified in patients with TB in China. NTM species identification is very important for distinguishing between tuberculosis and NTM pulmonary diseases, and the species diversity drives the creation of diverse and integrated identification methods with higher accuracy and efficacy.
Highlights
The Mycobacterium genus consists of species belonging to the Mycobacterium tuberculosis complex (MTBC), Mycobacterium leprae, and nontuberculous mycobacteria (NTM)
The prevalence of NTM diseases in China is rising as the incidence of the pulmonary disease which was predisposed to NTM is increasing [30, 31], and the coinfection of HIV contributed to this increase
The clinical symptoms and signs of NTM caused diseases are often hard to differentiate from those of MTBC-induced diseases, and the clinical NTM isolates are often of natural resistance to drugs that for TB infection treatment are linked to inadequate treatment in the public health system and the private hospital system, even in TB hospitals [32]
Summary
The Mycobacterium genus consists of species belonging to the Mycobacterium tuberculosis complex (MTBC), Mycobacterium leprae, and nontuberculous mycobacteria (NTM). The importance of NTM has recently increased and the pathogenic roles of many of these mycobacteria have been clearly defined [5]. Known reasons for this include (1) raising awareness, gaining more and more interests for these genera; (2) increased number of immunosuppressed patients including HIV; (3) increased number of patients with preexisting lung disease; and (4) mostly increased distribution of methods to detect NTM species [6, 7]. Identification of NTM has been conducted only in a few clinical laboratories in China, so misdiagnosis and incorrect treatment are commonly given to the patients infected with NTM. Once the anti-TB therapy fails, the treatment of NTM infection might be delayed several
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