COMPARATIVE ANALYSIS OF METHODS FOR IDENTIFICATION OF NONTUBERCULOUS MYCOBACTERIA ISOLATED FROM CLINICAL MATERIAL
Authors: Lyamin A. V. , Ismatullin D. D. , Zhestkov A. V. , Kovalyov A. M. , Baryshnikova L. A. , Nenjajkin S. S. 
Published: September 2017

Recently there has been a significant increase in the incidence of mycobacteriosis, which is due to an increase in the proportion of immunosuppressed patients, the presence of these various comorbid conditions, as well as the improvement of diagnostic methods. Selecting the most accurate method of identification is extremely important in determining treatment strategy of patients. The aim of the study was to conduct a comparative analysis of modern methods of identification NTMB isolated from clinical specimens in 2015 in the Samara region. The work was carried out identification of 78 strains of microorganisms. Laboratory diagnosis was carried out using the DNA hybridization method and MALDI-ToF mass spectrometry. When microbial identification using MALDI-ToF mass spectrometry was isolated 16 strains (20.5%) M. kansasii; 11 strains (14.1%) M. avium and M. fortuitum; 9 strains (11.5%) M. gordonae; strain 3 (3.8%) M. peregrinum, M. szulgai, M. chimera intracellulare group, strain 2 (2.6%) M. abscessus, M. septicum, M. paragordonae, M. senegalence, 1 strain (1.3%) M. chelonae, M. frederiksbergense, M. monacense, M. lentiflavum. By using mass spectrometry, it was identified 15 types NTMB compared with 9 types — by DNA hybridization. Full match identification results was observed only in 45 (57.7%) strains of divergent strains were found in 16 (20.5%). Most often when using the DNA hybridization method, discrepancy was detected in slow-growing cultures (9 strains) with a predominance of microorganisms identified as M. gordonae. Among the representatives of fast-growing NTMB, seven investigations were identified in the identification, more often among representatives of the M. fortuitum and M. peregrinum groups. Particular attention should be paid to the identification of the M. kansasii strain by a molecular genetic method, which mass spectrometry was defined as M. bovis. Both cultures of M. tuberculosis complex, which were identified by MALDI-ToF spectrometry, DNA hybridization were not determined to species. 17 (21.8%) of microbial strains which have been identified using the method of DNA hybridization, identified by spectrometry, including slow-growing microorganisms, non-mycobacteria strains seven (9.0%): Gordonia rubriperticta, Nocardia forcinica, Tsukumurella spp., Rhodotorula mucilaginosa. Accurate species identification NTMB is fundamental to determine the tactics of treatment of patients with mycobacteriosis. Due to this rather limited possibility of identification of non-tuberculous mycobacteria, using a DNA-hybridization method is inadequate to date. The introduction of new techniques, such as MALDI-ToF spectrometry, can identify a greater number of species of nontuberculous mycobacteria, as well as other types of slow-growing microorganisms having similarities with mycobacteria on cultural and morphological properties, which significantly increases the diagnostic capabilities of laboratories.