Ветеринария сегодня (Jun 2023)
Nontuberculous mycobacterium occurrence in biological material and environmental samples covered by epidemiological surveillance in the Republic of Dagestan
Abstract
An investigation for causes of tuberculosis occurrence and persistence on farms, as well as of continuous presence of tuberculin reactor animals on tuberculosis-free farms impeding allergy diagnosis revealed that the major cause is the persistence of pathogenic and nontuberculous acid-fast mycobacteria in the environment. To determine the occurrence of typical and atypical mycobacteria in samples covered by epidemiological surveillance, 222 biological material samples from cattle, 248 environmental samples (manure, soil, water from different sources, feedstuffs), 44 milk samples from tuberculosis-affected farms, 20 vaginal discharge samples from endometritis-affected cows and 405 sputum samples from tuberculosis-affected humans were tested. Isolation and identification were performed in accordance with the guidelines. Thirty-nine cultures were isolated from the pathological material; of these, 7 (17.9%) were identified as Mycobacterium bovis and 32 (82.1%) were identified as atypical mycobacteria. Among nontuberculous mycobacterium cultures, 16 (50.0%) were classified as belonging to group II, 2 (6.2%) – as belonging to group III and 14 (43.8%) – as belonging to group IV according to the Runyon classification. The following species were found to be predominant: group II – Mycobacterium scrofulaceum and Mycobacterium gordonae (scotochromogenous), group IV – Mycobacterium smegmatis and Mycobacterium fortuitum (rapidly growing). No mycobacteria were detected in milk samples and vaginal discharge samples from tuberculin reactor cows. From 405 sputum samples from tuberculosis-affected humans, 64 (15.8%) cultures were isolated, of which 55 (85.9%) were classified as Mycobacterium tuberculosis, 9 (14.1%) – as Mycobacterium bovis. Out of 248 environmental samples tested, mycobacteria were detected in 65 (26.2%) samples, of which 58 (89.2%) were atypical mycobacteria of groups II, III and IV; Mycobacterium bovis was isolated from 7 (10.8%) samples (soil and manure). The attempts to isolate Mycobacterium tuberculosis failed. The tests demonstrated the wide spread of nontuberculous acid-fast mycobacteria in the environment irrespective of the altitudinal zone. These findings constitute a basis for further monitoring of mycobacterium circulation in the environment in the Republic of Dagestan with a view of optimizing preventive measures.
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