The effectiveness of GenoType MTBDRplus using in the diagnosis of tuberculosis in Zaporizhzhia region

The method GenoType MTBDRplus, v.2 allows to study clinical material from positive and negative smears, to examine patients with new and previously treated cases of tuberculosis pulmonary and extrapulmonary localization. But now there is a small amount of researches concerning the use of this method in the diagnosis of tuberculosis. Aim. To evaluate the effectiveness of GenoType MTBDRplus, v.2 method using in clinical material research due to the diagnosis of tuberculosis in the Zaporizhzhia region in comparison with standard methods of investigation. Materials and methods. The analysis of 52 results of studies of clinical material using the GenoType MTBDRplus test system, v.2 from patients who were examined and treated in dispensaries of the Zaporizhzhia region in 2016 was carried out. There were 67.3 % of men and 32.7 % of women among the patients. The mean age of the patients was 46.0 ± 1.9 years. The study of the clinical material using the GenoType MTBDRplus test, v.2 was performed according to the standard instructions. Results. The results were positive in 12.5 % of the cases when tested by GenoType MTBDRplus, v.2 (p ˂ 0.05) among negative results of the microscopy of the clinical material. The proportion of coincidence between the cultural and molecular genetic methods was 90 % for sputum and 100 % for other clinical material. In the presence of multiresistance, both methods of investigation coincided in the number of detected cases (50 % for the GenoType MTBDRplus method, v.2 and 42.9 % for the cultural method, respectively, p ˂ 0.05). In comparison with the results of the cultural method, the GenoType MTBDRplus test, v.2 made it possible to establish resistance to rifampicin in 35.7 % (p < 0.05) of patients whose resistance was not determined. False-positive and false-negative results are due, perhaps, to the heterogeneity of strains of mycobacterium tuberculosis in clinical specimens, the absence of viable mycobacteria, the absence of phenotypic manifestations of mycobacterium tuberculosis genetic mutations, and errors in the investigations. The sensitivity of the GenoType MTBDRplus test, v.2 is about 78 %, but the specificity reaches 97 %. At the same time, the sensitivity of the test for multidrug resistance determining reaches 100 %, the specificity is about 89 %. The greater positive predictive value for cases in which the DNA of mycobacteria is determined and the negative predictive value is for cases in which multidrug resistance is determined. Conclusions. This indicates that the using of the GenoType MTBDRplus test, v.2, together with the cultural method of investigation, has a high diagnostic value, high sensitivity (100 %) and specificity (89 %) for the definition of multiresistance, and makes it possible to obtain a result in a short time compared to culture. tuberculosis; diagnostic techniques and procedures; genotype; efficiency