Treatment outcomes in new pulmonary tuberculosis cases depending on the main genotypes of <i>Mycobacterium tuberculosis</i> in the Republic of Sakha (Yakutia)

Abstract

The objective: to study treatment efficacy in new pulmonary tuberculosis patients depending on the genotypes of M. tuberculosis in the Republic of Sakha (Yakutia). Subjects and methods . The authors studied the clinical course and outcomes of 312 bacteriologically confirmed new pulmonary tuberculosis cases among patients admitted to hospital in 2010-2014. Molecular genetic tests included deletion analysis of RD105 and RD207 regions of DNA of the pathogen followed by MIRU-VNTR genotyping at 24 loci. Results. In the Republic of Sakha (Yakutia), the Bejing and S genotypes are of epidemic importance, these genotypes prevail among drug resistance mycobacteria. Tuberculosis caused by the Bejing genotype had multiple (MDR) and extensive drug resistance (XDR) in 30.6% of cases, its subtype CC2/W148 - in 85.3%. The S genotype was accompanied by MDR/XDR in 69.7% of cases, subtype S256 - in 78.9%. The treatment of patients was highly efficient according to the criteria of sputum conversion (92%) and cavities healing (89.4%). The lowest rates were observed in case of tuberculosis caused by the Bejing and S genotypes due to their subtypes CC2/W148 and S256. Clinical cure of new pulmonary tuberculosis caused by the Bejing genotype was achieved in 73.4% of cases, by subtype CC2/W148 - in 41.2% with a significantly higher proportion of treatment failures and lethal outcomes of tuberculosis than in other subtypes of this genotype. With the S genotype, the clinical cure was achieved in 72.7% of patients, with no significant difference in the incidence of unfavorable outcomes in patients with subtype S256.