Simultaneous detection of XDR genetic determinants and Mycobacterium tuberculosis genotyping by TB-TEST

Introduction: Due to the limited choice of drugs against MDR and XDR Mycobacterium tuberculosis (MTB), detection of mutations connected with a certain MTB resistance level is necessary for the therapy optimization. Materials and Methods: We studied 247 MTB strains obtained from 108 new-detected and 139 previously treated patients. Drug susceptibility testing (DST) was done by TB-TEST (LLC “BIOCHIP”Russia), BACTEC MGIT 960, Sensititre MycoTB Plate. Aim: The study was aimed at finding a correlation between results of molecular and microbial DST. Results: Most of MDR, XDR and R-resistant strains had S531L mutation in rpoB led to the high resistance to rifampicin (R). MTB strains with D516Y, H526L, H526N, L533P and L511P mutations had intermediate resistance. 90% of MDR, XDR and isoniazid (H)resistant strains had mutation S315T in katG leading to the high resistance to H. ≈ 3,0% of strains had T15 in inhA led to low/moderate resistance. High resistance to ofloxacin (OFX) and moxifloxacin (MFX) connected with D94G, N, Y, H mutations; moderate resistance to OFX and low to MFX connected with A90V, S91P, D94A mutations in gyrA, and low/moderate resistance connected with mutations in gyrB. Previously treated patients had high resistant MTB strains with double mutations in gyrA. eis mutations detection increased a correlation with Bactec MGIT 960 up to 93,2%. Beijing MTB strains detected in 78,0% of cases. 20,0% of them were BO/W148 and associated with the high resistance to drugs. LAM, E-A Line, Ural, and Haarlem genotypes detected in 7,7%, 4,6%, 3,9%, and 1,9% of cases respectively. Conclusion: TB-TEST helps to get reliable DST results and monitor MTB spreading in Moscow