Detection of Nontuberculous Mycobacteria in the Republic of Mari El: Etiological and Epidemiological Characteristics

Introduction: Nontuberculous mycobacteria are widespread in the environment and their pathogenic species can cause mycobacteriosis, especially of the respiratory system.

Objective: To study of the species diversity of nontuberculous mycobacteria and to give an epidemiological description of cases of isolation of nontuberculous mycobacteria in the Republic of Mari El in 2015–2024.

Materials and Methods: The conducted retrospective epidemiological study was descriptive and evaluative. We analyzed anonymized records of 30,617 patients seeking care at tuberculosis and general health facilities of the Republic of Mari El in the years 2015 to 2024. The statistical analysis was performed using StatTech v. 4.8.2 by StatTech LLC, Russia.

Results: We identified 544 people with nontuberculous mycobacteria (mean age = 60 years), most of whom were men (284; 52.2 %). We established that 338 (62.1 %) patients were urban residents and 206 (37.9 %) lived in the countryside. Nontuberculous mycobacteria were repeatedly isolated from 156 (28.7 %) and only once – from 388 (71.3 %) cases. The most common species included M. gordonae (n = 168; 29.5 %), M. intracellulare (n = 122; 21.4 %), and M. avium (n = 81; 14.4 %). At this, 104 patients (19.1 %) were diagnosed with mycobacteriosis, of which 63 (60.6 %) were women. In most cases, mycobacteriosis was induced by slow-growing M. intracellulare, M. avium, and M. gordonae. The analysis of the number of patients showed a 4.9-fold increase. Most cases with isolated nontuberculous mycobacteria lived in the city of Yoshkar-Ola (n = 295, 54.2 %), Medvedevsky (n = 61, 11.2 %) and Zvenigovsky (n = 33, 6.1 %) districts, the town of Volzhsk (n = 30, 5.5 %), Sovetsky (n = 19, 3.5 %) and Volzhsky (n = 17, 3.1 %) districts.

Conclusions: Our study allowed us to determine regional characteristics of nontuberculous mycobacteria isolated from human specimens and establish the prevalence of slow-growing species in the Republic of Mari El.

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