Journal of
Microbiology and Antimicrobials

  • Abbreviation: J. Microbiol. Antimicrob.
  • Language: English
  • ISSN: 2141-2308
  • DOI: 10.5897/JMA
  • Start Year: 2009
  • Published Articles: 166

Full Length Research Paper

Multiple-mutations in the katG encoding catalase proxidase in isoniazid resistant Mycobacterium tuberculosis isolates correlate with high-level of resistance in patients with active pulmonary tuberculosis in Iran

M. Karim Rahimi3 S. Zaker bostanabad1, 3, 4*, P. Adimi3, M. Shekarabei4, 6, M. Habibollah4, F. Shirmohammadi4, Kh. Bigdeli4, A. Faraji4, B. Delalat4, Z. Tayebi3, M. Masoumi3, E. Jabbarzadeh2, Sh. Pourazar2 and L. P. Titov5
1Islamic Azad University, Parand Branch, Biology and Microbiology Department, Iran. 2Pasteur Institute of Iran, Mycobacteriology and Pulmonary Research Department, Iran. 3Islamic Azad University, Tehran Medical Branch, Microbiology Department, Iran. 4Masoud Laboratory, Microbiology Department, Islamic Azad University, Iran. 5Belarusian Research Institute of Epidemiology and Microbiology, Clinical Microbiology, Belarus. 6Iran Medical University, Immunology Department, Iran.
Email: [email protected]

  •  Accepted: 22 September 2009
  •  Published: 30 October 2009


The aim of this study was to investigate the significance of multiple-mutations in the katG gene, predominant nucleotide changes and its correlation with high level of resistance to isoniazid in Mycobacterium tuberculosis isolates that were randomly collected from sputa of 42 patients with primary and secondary active pulmonary tuberculosis from different geographic regions of Iran. Drug susceptibility testing was determined using the CDC standard conventional proportional method. DNA extraction, katG gene amplification and DNA sequencing analysis were performed. Thirty four (80%) isolates were found to have multiple-mutations (composed of 2 - 5 mutations) in the katG gene. Increased number of predominant mutations and nucleotide changes were demonstrated in codons 315 (AGC→ACC), 316 (GGC→AGC), 309 (GGT→GTT) with a higher frequency among patients bearing secondary tuberculosis infection with elevated levels of resistance to isoniazid (MIC µg/ml ≥ 5 - 10). Furthermore it was demonstrated that the combination of mutations with their predominant nucleotide changes were also observed in codons 315, 316 and 309 indicating higher frequencies of mutations among patients with secondary infection respectively. In this study 62% (n = 21) of multi-mutated isolates found to have combination of mutations with predominant nucleotide changes in codons 315 (AGC→ACC), 316 (GGC→GTT), 309 (GGT→GGT) and also demonstrated to be more frequent in isolates of patients with secondary infections, bearing higher level of resistance to isoniazid (≥ 5 – 10 µg/ml). 

Key words: Predominant mutation, Mycobacterium tuberculosis, high level resistant to izoniazid, Iran.