Use of genotype MTBDR assay for detection of isoniazid and rifampin resistance in mycobacterium tuberculosis complex isolates

Mycobacterium tuberculosis is one of the leading causes of death due to an illness worldwide. Multidrug resistant tuberculosis is associated with a high case fatality rate. The rapid detection of antibiotic resistance in Mycobacterium tuberculosis complex isolates is an important challenge to ensure a rapid and adequate therapy of tuberculosis. World Health Organisation recommends testing of 100% of previously treated tuberculosis patients for multi drug resistance, as well as testing of any new tuberculosis patients considered at high risk of having multi drug resistant tuberculosis. The Genotype MTBDR is a multiplex PCR DNA strip assay designed for the rapid detection of rpoB and katG mutations in clinical isolates. The aim of this study was to evaluate Genotype MTBDR as a rapid assay to detect RIF and INH resistance.A total of 50 M. tuberculosis complex strains isolated from different clinical specimens in Fırat University Hospital Microbiology Laboratory were used in this study. Antimicrobial susceptibility testings for INH and RIF were performed by BACTEC 460TB and Genotype MTBDR assay. The results of Genotype MTBDR assay were compared with gold standart BACTEC 460TB. Eleven (22%) out of 50 strains were INH resistant and 3 (6%) strains were both INH and RIF resistant by BACTEC.Thirty nine (%78) strains were susceptible to both INH and RIF. Eight (72,7%) out of 11 INH resistant isolates and all of 3 MDR isolates (100%) were correctly identified by Genotype MTBDR assay.Sensitivity of Genotype MTBDR assay to detect INH and RIF resistance were 78,6 and 100%, respectively. Specifity of the test were 100% for both drug. The results of this study indicate that the Genotype MTBDR assay has an overall good performance and sensitivity for rapid detection of RIF and INH resistance.Keywords: Multi drug resistance tuberculosis, Mycobacterium tuberculosis complex, rpoB, katG, Isoniazid, Rifampin.