Abstract
The incidence of non-tuberculous mycobacteria (NTM)-related death has increased globally recently. To obtain information of the species and characterization of pathogens involved in NTM pulmonary infection in Southern-central China, we identified 160 non-tuberculous infection cases from 3995 acid-fast bacilli (AFB)-positive tuberculous suspects. We then randomly selected 101 non-tuberculous patients, isolated bacteria from their sputa and genotyped the pathogens using the 16S rRNA gene and 16S-23S rRNA internal transcribed spacer sequences. M. intracellulare (32.67%, 33/101), M. abscessus (32.67%, 33/101) and M. fortuitum (7.92%, 8/101) are identified in these isolates. Surprisingly, non-mycobacteria including Gordonia (8.91%, 9/101), Nocardia (5.94%, 6/101) and Tsukamurella (0.99%, 1/101) are also discovered, and the case of Tsukamurella pulmonis infection is first discovered in Southern-central China. Moreover, species of M. mucogenicum group, M. chubuense, M. kansasii, M. gastri, M. avium, M. porcinum and M. smegmatis are identified. In addition, nine immune compromised cases (8.91%, 9/101), including type two diabetes mellitus and HIV/AIDS are found to be infected with non-tuberculous bacteria. This study revealed the distribution and characteristics of non-tuberculous AFB pathogen infection occurred in Southern-central China, and suggested that physicians should be alert of the emerging of NTM and non-mycobacteria infection in AFB positive cases and take caution when choosing chemotherapy for tuberculosis-like pulmonary infections. Generally, this study may help with the development of new strategy for the diagnosis and treatment of mycobacterial infection.
Highlights
Mycobacteria that do not contain Mycobacterium tuberculosis (MTB) complex and that do not cause Hansens disease are known as non-tuberculous mycobacteria (NTM)
The most common pulmonary non-tuberculous mycobacterial pathogens are M. avium, M. intracellulare, M. chelonae, M. abscessus and M. fortuitum, while their species and prevalence vary with the geographical locations [3, 4]
Isolates that could grow in both p-nitrobenzoic acid (PNB) and thiophene-2-carboxylic acid hydrazide (TCH) modified L-J medium were considered as NTM, which were subsequently genotyped by 16S rRNA gene and internal transcribed spacer (ITS) sequencing
Summary
Mycobacteria that do not contain Mycobacterium tuberculosis (MTB) complex and that do not cause Hansens disease are known as non-tuberculous mycobacteria (NTM). 16S rRNA gene analysis is the standard method for identification of mycobacteria. Limitation of the analysis is evident because some NTM species share the same or very similar 16S rRNA sequence [8], and the basal sequence diversity within the genus Mycobacterium is rather low. ITS is used as ideal target genes in classification and identification of mycobacterial intra-species and ITS sequence serves as an effective supplement for identification of closely related species that 16S rRNA gene sequence can not differentiate[9]. Non-tuberculous acid fast isolates were collected from the sputa of tuberculosis suspects in Southern-central China and were characterized based on the 16S rRNA gene and ITS sequence. The information presented here will increase awareness of Chinese clinicians about NTM
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