Objective: To design a rapid test to detect the rifampin (RIF) and isoniazid (INH) resistant mutant based on polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique that analyzes the katG, rpoB genes.
Methods: Biochemical test as well as IS6110 targeting PCR revealed 103 clinical samples were tuberculosis. To determine the susceptibility of isolates to anti TB drugs, the proportional method was used. Mutations presented within the amplified products of the katG, rpoB genes were evaluated by SSCP.
Results: Using proportional method, 12 (11.6%) and 9 (8.7%) isolates were resistant respectively to INH and RIF and 9 (8.7%) isolates showed resistance to both drug (multi-drug resistant tuberculosis). Three (2.9%) multi-drug resistant tuberculosis and two INH resistant isolates were detected by the PCR-SSCP and sequencing. The sensitivity and specificity of PCR-SSCP for multi-drug resistant isolates were 33% and 100%, respectively.
Conclusions: Complete agreement between SSCP and sequencing can indicate that resistance-associated mutations have occurred in other genes except our considered genes.
Keywords: Drug resistance; Mycobacterium tuberculosis; PCR-SSCP; Phenotypic method; katG; rpoB.