Abstract
The aim of this study was to explore baseline data, laboratory and molecular analyses to determine if any could serve
as potential prognostic marker(s) for treatment response to second line tuberculosis regimens. Of a total number of
50 multi-drug resistant tuberculosis (MDR-TB) patients starting second-line drug MDR-TB treatment in Iraq, only
21 showed treatment adherence and thus, included in this study. Response to treatment was monitored for 11 months by
sputum microscopy and culture. We explored baseline data, laboratory and molecular analyses to determine if any could
serve as potential prognostic marker(s) for treatment response. Highly signifi cant association (P = 0.019) was detected
between mutations in katG315 codon and good response to second-line anti-TB drugs. Spoligotyping and mycobacterial
interspersed repetitive unit variable number tandem repeat confi rmed that katG315-mutatnt isolates were genotypically
unrelated. The katG315 mutation is a potential prognostic marker for treatment response to second-line anti-tuberculosis
drugs. One possible explanation of our results is that the katG315-mutants are sensitive to bacterial killing by “oxidative
killing.”
Key words: KatG315, multi-drug resistant, second-line drugs, tuberculosis
