Genotyping of mycobacterium tuberculosis complex isolates resistant to primary antituberculosis DRUGS by molecularmethods

Aim: Genotype determination of Mycobacterium tuberculosis complex (MTBC) isolates, which were phenotypically resistant to primary anti-tuberculosis drugs, by spoligotyping and Mycobacterial interspersed repetetive units, (MIRU) - variable number of tandem repeat (VNTR) typing methods was aimed. Materials and Methods: MTBC strains isolated from clinical materials in Dicle University Hospital Laboratory Mycobacteriology unit and found to be resistant to primary antituberculosis drugs with the MGIT 960 system between January 2014 and August 2019 were included. Of the 69 isolates, 32 (46.4%) were multi-drug resistant (MDR), 34 (49.3%) were resistant to one or more of the primary anti-tuberculosis agents in addition to isoniazid (INH), and three (4.3%) were resistant to rifampin (RIF). Isolates were evaluated in terms of genotypic diversity and clonal associations by spoligotyping and 15 loci MIRU-VNTR methods. Resistance genes were determined by GenoType MTBDR plus (Hain Lifescience, Germany). Results: Families with the highest number of members by spoligotyping were T1 (55.4%) and TUR (13.8%). Approximately one-third (36.92%) of the isolates clustered in SIT53 of T1 family, 9.23% in SIT284, 12.31% in SIT41, and 0.77% in the spoligotype SIT2560, which was not included in any family. Seven isolates were identified as SIT2560, one isolate SIT4, SIT608 and orphan strain. TCG/TTG mutation in the 531st gene region of the rpoB gene, found in 19 (57.6%) of the RIF resistant isolates, was the most detected mutation responsible for resistance. AGC/ACC mutations were found in the katG315 gene region in 14 (46.7%) of the INH resistant isolates, and C/T mutations were detected in the -15 position of the inhA gene region in 8 (26.7%) of the INH resistant isolates. Conclusion: The major families in which our isolates clustered were T1 with 55.4% and TUR with 13.8%, the clusters determined were generally mixed isolates from patients from different provinces and there was no clonal relationship between them, and resistant isolates showed common mutations stated in the literature.