Sana Hafeez, Haleema Sajid, Farouk Qamar Malik, Imran Ali Zaidi, Sobia Niaz, Amna Iqtidar
Background: Tuberculosis (TB) is fatal and life
threatening infectious disease. The transmission rate of tuberculosis is very
high. Various drugs are used as treatment for TB. Recently it has been observed
that one of the most important factor for fast TB spread is development of
anti-TB drug resistant mycobacterium tuberculosis (MTB). Various combination of
drugs like isoniazid (INH), rifampicin (RIF), Streptomycin(SM), pyrazinamide
(PZA) or ethambutol (EMB) are in global use for TB treatment. Improper usage of
these drugs makes the person prone to develop anti-TB drug resistant
Aim: To evaluate association of embB gene with ethambutol
resistance in Mycobacterium Tuberculosis.
Methods: 104 Specimens
of sputum from suspected tuberculosis patients were processed for inoculation
in Lowenstein J Medium after it has been decontaminated
properly. Kit method by using QIAamp DNA Mini kit was utilized for extraction
of DNA. Then region from base 6953 to 10249 of embB
gene was amplified through PCR and then followed by sequencing with the aid of
softwares blast2seq and ClustalW2.
Three primer sets were utilized to amplify embB gene. Ethambutol (EMB) Resistant MTB specimens were
processed to study mutation in embB gene.
Results: Out of the
total 104 sputum specimens, 14 samples were found to have ethambutol
resistance. These 14 samples were then processed for mutational analysis. DNA
sequence analysis of these 14 samples confirmed embB gene mutation in 10
samples. Mutational analysis revealed
that 08 samples showed mutation at codon 306 and two samples showed mutation at
319 codon. The reported mutation Methionine →Isoleucine
was seen in 07 samples with ATG codon replaced by ATA codon at codon position
306. One sample showed mutation as Methionine →Isoleucine
with ATG codon replaced by ATC codon at codon position 306. Two samples showed
mutation as Tyrosine →Serine with TAT codon replaced by
TCT at 319 codon position in embB gene.
concludes that mutation of certain genes particularly point mutation of embB
gene at codon 306 and 319 is associated with drug resistance of ethambutol in
ethambutol resistant mycobacterium tuberculosis patients.