Identification of non-tuberculous mycobacteria from 2021 to 2022 in a center of Tianjin
Objective To investigate the species and distributions of non-tuberculous mycobacteria(NTM)among outpatients with pulmonary infection,explore the type and distribution of NTM species.Methods A total of 14 414 respiratory specimens from suspected pulmonary tuberculosis patients who visited the outpatient clinic of the Tianjin Tuberculosis Control Center from January 2021 to December 2022 were collected for mycobacterial culture(BACTEC MGIT 960 and modified Roche method),and 1 838 culture-positive specimens were included.Mycobacterium tuberculosis antigen MPT64(colloidal gold method)was used for bacterial strain identification.For samples with negative MPT64 test results or positive but questionable MPT64 results,Roche medium was used for inoculation.After initial screening with acid-fast staining,DNA microarray chip technology was used for mycobacterial species identification.Undetermined strains were further identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS).The distribution characteristics of NTM strains in different ages,genders,and different types of NTM strains after excluding duplicates were retrospectively analyzed.Results Among 1 838 positive cultures in 2021-2022,there were 1 289 non-repeated positive isolates(excluding repeated cultures).With using four identification methods,315 NTM isolates were isolated from 313 specimen and then the NTM rate was 24.44％(315/1 289).Among the NTM isolates,the top four constituent ratios were Mycobacterium intracellulare 26.03％(82/315),Mycobacterium lentiflavum 20.00％(63/315),Mycobacterium abscessus 16.19％(51/315),and Mycobacterium kansasii 10.79％(34/315).There were 190 male NTM-infected patients and 123 female NTM-infected patients,with a ratio of 1.54:1.Among the age distribution of four major NTM isolates,M.abscessus isolates were common among young patients while M.intracellulare isolates were common among old patients.Conclusions The NTM isolation rate in our center was high,and the distribution of NTM was diverse.The dominant strains were mainly Mycobacterium intracellulare,Mycobacterium lentiflavum,Mycobacterium abscessus,and Mycobacterium kansasii.
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