Comparative effectiveness of different molecular genetic methods in the diagnosis of tuberculosis

Aim is to compare the effectiveness of using different molecular genetic methods in the diagnosis of tuberculosis and the determination of drug sensitivity to rifampin (Rif). Material and Methods. A retrospective analysis of the results of a study of sputum samples obtained from 1992 patients with pulmonary tuberculosis treated in the Saratov Regional Clinical TB Dispensary was carried out from 2014 till 2018. The following methods were used: real-time polymerase chain reaction (PCR Real Time), biological microchips, automated Xpert® MTB / Rif technology. Statistical processing of the research results was carried out using the Bayes formula based on the tables of mutual contingency of the “four-field table” and the χ2 test. When determining the significance of differences in relative values, a critical significance level of 0.05 was taken. Results. A higher diagnostic sensitivity of the Real Time PCR methods (73.9 %) and biological microarrays (70.3 %) was established compared to the Xpert® MTB / Rif method (34.2 %) (p<0,001) in the etiological diagnosis of tuberculosis. The sensitivity of the methods depended on the massiveness of bacterial excretion and clinical form of tuberculosis. Conclusion: In accordance to lower diagnostic sensitivity of the Xpert MTB / Rif method in verifying the diagnosis of tuberculosis in determination of drug resistance to Rif using the Xpert MTB / Rif method, rather high operational characteristics were found out (sensitivity — 89.7 %, specificity — 89.1 % and efficiency — 89.4 %) comparable with the method of biological microarrays (93.9 %, 71.8 %, 82.9 %) (p=0.127, p<0.001, p=0.139) respectively.