Tuberculosis is a major infectious disease killing nearly two million people, mostly
in developing countries, every year. The increasing incidence of resistance of Mycobacterium tuberculosis strains to the most effective anti- TB drugs is a major factor
contributing to the current TB epidemic. Drug-resistant strains have evolved mainly due
to incomplete or improper treatment of TB patients. Resistance of M tuberculosis to anti-
TB drugs is caused by mutations in gene encoding drug targets. According to the World
Health Organization, 8 million cases of tuberculosis (TB) occur each year, resulting in 2
million deaths. TB is. transmitted by sneezing, coughing, speaking by those persons
having already TB. In affected persons mycobacterium multiplies and spread by
lymphatics to the lymph nodes, and through the bloodstream to other body sites.
Pulmonary TB is a very common type of TB. The worldwide failure of TB control
programs, combined with the HIV /acquired immunodeficiency syndrome pandemic, led
to marked increases in TB mortality. Pakistan is 1 of 22 countries listed by the World
Health Organization (WHO) as having a high incidence of tuberculosis. TB is responsible
for 5.1 percent of the total national disease burden in Pakistan. In this study sputum
samples from TB patients were collected in wide mouth, transparent containers from
local sources of Lahore. Sputa were processed with Sodium hydroxide solution to remove
contamination and inoculated directly onto two slopes 'of Lowenstein-Jensen (LJ) Medium in tubes. After inoculation samples were incubated at 37°C up to eight weeks or
till colonies appear. Colonies grown on the slopes were identified as MTB by sensitivity
and identification tests. DNA was extracted and .amplified with specially designed
primers and sequencing of the peR products was also done. Analysis of the sequences
and SNPs/mutations was done with the help of appropriate bioinformatics softwares.
DNA extraction was done in Institute of Public Health, Lahore and all remaining work
was performed in Molecular Cytogenetic and Genomics Laboratory, (IBBT), UV AS,
Lahore. Present study was related to polymorphism analysis of embB gene of MTB
isolates and its association with ethambutol resistance. From total 14 resistant samples
ten samples showed reported mutations when the query sequences were compared with
the reported reference sequence of Mycobacterium tuberculosis embB gene available on
NCBI website. None of the novel mutation was found. EMB resistant MTB strains
showed mutations in embB gene at different co dons including 306 codon and 319 codon.
Genetic analysis showed that eight samples possessed mutation at 306 codon and two had
at 319 codon. WIllie four samples did not show any mutation or alteration in embB gene
region. Patients were screened for alternations in codon 306 of the embB gene as
mutation in this codon are reported to confer resistance to ethambutol.