Research Article 
Haider H. Mitab¹, Abir Muhssan Jabar Al Zaydi
Abstract
Multidrug-resistant tuberculosis (MDR-TB) is a global problem that many countries are
challenged with. Rapid and accurate detection of MDR-TB is critical for appropriate treatment
and controlling of TB. the aims of study at using Polymerase Chain Reaction for detection of
multidrug-resistant Tuberculosis from cultured samples A total of 30 M. tuberculosis isolates
from cases with diagnosed TB by GeneXpert, AFB and Culture on L. J media after incubation
period from 3-8 weeks, DNA extraction from bacteria colonies. Resistant isolates were tested
for characterization of mutations in the rpoB, KatG InhA1 and IhA2 genes by Real Time PCR .
The results of the real time PCR showed that mutations of genes (rpoB, katG, inhA1 and
inhA2) that were responsible for resistance to rifampicin and isoniazid. The test showed
positive results for resistance genes (20%, 10%, 6.6%, 10% Respectively) as well as note that
the values of Ct for this test ranged from (12-38.25), and the melting points of the genes were
between (85-88.5 Co). Real time PCR results identified three mutations of MDR (rifampicin
and isoniazid) resistance genes, whereas there was one MDR mutation of molecular
diagnostic results with the GeneXpert MTB/RIF test for rifampicin. When comparing the results
of the Real time PCR and GeneXpert tests at the level of the genetic mutation with rifampicin,
the real time PCR test showed four resistance mutations for the rpoB gene for both new cases
and relapse tuberculosis as well as one rpoB mutant for under treatment patient. Both
molecular tests have agreed to identify one rpoB mutant in the case of failure TB treatment
Key words: Multidrug-resistant tuberculosis (MDR-TB); GeneXpertMTB/RIF; rpoB