Significance of initial isoniazid resistance for outcome of standard TB treatment and its detection by line-probe assays

To document the impact of isoniazid (INH) resistance non-MDR on outcome of World Health Organization (WHO) recommended regimens. To check whether rifampicin (RIF) resistance missed by phenotypic drug susceptibility testing (DST) can explain the apparently worse first-line treatment outcomes with initial INH polyresistance.
To confirm that line-probe assays targeting the inhA and katG genes indicate frequent non-effectiveness of INH in the shorter MDR regimen due to high level resistance when mutations in both genes are present, as opposed to only a katG mutation.
The data generated by the studies will be very useful to improve or correct current WHO recommendations on standard regimens.