Genotyping of Related Mutations to Drug Resistance in Isoniazid and Rifampin by Screening of katG, inhA and rpoB Genes in Mycobacterium tuberculosis by High Resolution Melting Method

Introduction: Tuberculosis is one of the infectious diseases and this is responsible for 3 million mortalities in the world which is increased by the rise of drug-resistant tuberculosis patients. Thus, it seems essential to detect the drug resistances in tuberculosis patients. Rifampin and isoniazid are two essential drugs for treatment of tuberculosis patients. The new High Resolution Melting method is simple, rapid and inexpensive for detection of these mutations responsible for these resistances compared to conventional methods in tuberculosis patients. Materials and methods: 2500 sputum samples were collected from patients with suspected tuberculosis referred to Iran Remedial Center over a period of 2 years in which, 1650 samples had positive smear for Mycobacterium tuberculosis. After extraction of genomic DNA from samples, High resolution melting method was used for samples based on the color of SY to-9 and PCR product were sequenced to verify the mutation. Results: Our findings showed that, 116 out of 1650 positive smear samples, were resistant to isoniazid due to mutations in katG and inhA genes, which this resistance is created by mutation of 20 samples in inhA gene and 96 samples in katG gene. Whist 65 samples had resistance to rifampin with mutation in rpoB gene. Conclusion: High resolution melting method is quick, easy and affordable without wasting time for culturing and Post PCR processes for diagnosing these resistances in tuberculosis clinical samples.