Frequency of mutational changes in the embB among the ethambutol-resistant strains of Mycobacterium tuberculosis in Iran

  • Faranak Rezaei School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  • Mehri Haeili Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
  • Parviz Mohajeri Kermanshah University of Medical Sciences, Kermanshah, Iran
  • Abdolrazagh Hashemi Shahraki Pasteur Institute of Iran, Tehran, Iran
  • Abbas Ali Imani Fooladi Baqiyatallah University of Medical Sciences, Tehran, Iran
  • Fatemeh Zahednamazi School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  • Mohammad Mehdi Feizabadi School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Keywords: Mycobacterium tuberculosis, embB, ethambutol, spoligotyping, Beijing

Abstract

Introduction: Early detection of drug resistant tuberculosis is one of the main priorities of TB control program. Ethambutol (EMB) is a first-line anti-TB drug that is effective for preventing treatment failures caused by Mycobacterium tuberculosis strains that are resistant to other drugs. The aim of this study was to sequence the embB gene to characterize the mutations causing resistance to EMB and to analyze the relationship between bacterial genotype and EMB resistance among M. tuberculosis isolates in Iran.

Methodology: A total of 20 M. tuberculosis isolates comprising 10 multidrug-resistant (MDR) and 10 non-MDR isolates, recovered from TB patients in four regions: Tehran, Isfahan, Zahedan, Khorasan, were analyzed. Mutational profiling was performed by amplifying and sequencing the embB gene. Spoligotyping was carried out to characterize the bacterial genotype.

Results: Phenotypic EMB resistance was found in 13 strains. Mutations affecting ethambutol resistance-determining region (ERDR) of the embB were identified in 6 of 13 EMB-resistant isolates. The majority of these mutations resulted in amino acid substitution at position 306 (M306V). A novel mutation at codon 366 was identified (S366L) in one isolate. Ural was the most predominant genotype in the studied population. Beijing genotype was associated with both MDR and EMB resistance in which all mutations occurred at codon 306 of the embB gene.

Conclusion: A significant association between Beijing genotype and EMB resistance was found, mainly due to mutations at embB306. Results of this study can be used as a basis to develop or improve rapid molecular tests to monitor drug-resistant strains in this country.
Published
2016-04-28
How to Cite
1.
Rezaei F, Haeili M, Mohajeri P, Hashemi Shahraki A, Imani Fooladi AA, Zahednamazi F, Feizabadi MM (2016) Frequency of mutational changes in the embB among the ethambutol-resistant strains of Mycobacterium tuberculosis in Iran. J Infect Dev Ctries 10:363-368. doi: 10.3855/jidc.7215
Section
Original Articles