• Detection of isoniazid resistance strains of Mycobacterium tuberculosis by multiplex allele-specific polymerase chain reaction (MAS-PCR) in Ardabil, Iran
  • Zahra hosseinali,1 Jafar mohammadshahi,2,* Mehran sadeghi,3
    1. Department of Microbiology, School of Medicine, Ardabil University of Medical Science, Ardabil, Iran
    2. Department of Infectious Diseases, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran
    3. Student research committee, School of Medicine, Ardabil University of Medical Science, Ardabil, Iran


  • Introduction: Mycobacterium tuberculosis (MTB) is the major causative agent of a highly contagious disease called tuberculosis (TB). Tuberculosis (TB) is one of the top 10 causes of death among poverty-related infectious diseases (IDoPs), a major public health problem worldwide and is one of the most common life-threatening infections, with high rates of multidrug-resistant tuberculosis (MDR-TB). Drug-resistant tuberculosis (DR-TB) occurs in many parts of the world. The global rise of drug-resistant MTB strain, especially the significant prevalence of isoniazid (INH)-resistance, constitutes a significant challenge to global health. Isoniazid is one of the first-line drugs for tuberculosis treatment, and there are increasing reports of the development of resistance to this drug in many parts of the world. In most cases, mutations in the KatG and inhA genes are the cause of isoniazid resistance. Efforts to control tuberculosis have encountered serious problems with the emergence of drug-resistant Mycobacterium tuberculosis (MT), and rapid diagnosis of resistance can play an essential role in controlling and preventing the disease. Therefore, this study was conducted to evaluate the prevalence of mutations in genes associated with isoniazid (INH)-resistant MTB in Ardabil, Iran.
  • Methods: In this cross-sectional study, 111 Sputum and bronchoalveolar lavage (BAL) samples which microscopically were positive for MTB, were collected from patients referred to Ardabil Province Health Center from July 2016 to June 2020. Clinical specimens were subjected to DNA extraction using a specific lysis buffer and boiling method. The multiplex allele-specific polymerase chain reaction (MAS- PCR) and specific primers were employed for identifying mutation in inhA and KatG genes.
  • Results: Overall, based on the MAS-PCR method, 23(20.71%) of infected samples were resistant to isoniazid. The frequency of mutations in KatG and InhA genes was 10.81% and 9.9%, respectively.
  • Conclusion: This study showed the high mutation rate in the KatG gene which would be valuable for providing appropriate treatment regimens and tuberculosis management. Detection of resistance alleles in the KatG and inhA genes for INH could serve as markers for MDR-TB strains. The MAS-PCR is a useful method to detect mutations in the KatG and inhA genes. this molecular method is not only simple and inexpensive but also provides accurate and reliable results in less time than other methods. In addition, rapid diagnosis of INH-resistant MTB would accelerate the modification of TB treatment regimens. Timely infection control measures could reduce the risk of the development and transmission of multidrug-resistant TB.
  • Keywords: Mycobacterium tuberculosis, Isoniazid (INH), Drug resistance , tuberculosis (TB)