Detection of Ethambutol-Resistant Associated Mutations in Mycobacterium tuberculosis Isolates from Iran Using Multiplex Allele-Specific PCR

Tuberculosis is a serious global public health problem and its high prevalence is stron gly associated with the enhancement of drug resistance. In this study we demonstrate a multiplex allele-specific polymerase chain reaction (MAS)-PCR assay to simultaneously detect mutations in the first and third bases of the embB gene codon 306 ATG in ethambutol (EMB) resistant isolates of Mycobacterium tuberculosis. A total of 5029 patients were sampled between 2010 and 2012. All the specimens were examined microscopically for acid-fast bacilli and cultured in Löwenstein-Jensen medium. The susceptibility tests were performed for culture positive samples and the EMB resistant M. tuberculosis isolates were subjected to MAS-PCR targeting embB gene in the codon 306 ATG. Frothy eight of 176 isolates were EMB-resistant. None of the isolates showed mutation in the first base of the codon 306 ATG, but mutation in third base of the codon 306 ATG was detected in 14 isolates. We observed a correlation between culture-based phenotypic drug susceptibility and MAS-PCR method. The absence of mutation in resistant isolates can be attributed to possible involvement of other codon position at the same gene or other genes.