Molecular characterization of Isoniazid and Rifampicin resistance strains of Mycobacterium tuberculosis isolated from new tuberculosis cases in Lagunes Region (Cote DIvoire)

Tuberculosis remains in the world an important problem of public health. This study objective was to investigate the genetic basis of resistance to Isoniazid and Rifampicin of Mycobacterium tuberculosis complex strains collected in Lagunes region, an area of high burden of tuberculosis. During primary resistance study, 196 smears positive new cases of tuberculosis were recruited in Lagunes region. Out of a sample of 31 strains, 17 were Isoniazid mono-resistant strains, 7 were multi-drug resistant (MDR) strains and 7 were susceptible to both Isoniazid and Rifampicin. Genotype MTBC assays and sequencing of mabA-inhA regulatory region, katG, inhA and rpoB genes were performed on all the strains. At least one mutation in the genes studied was found in 20 (83%) of the 24 resistant strains. Ser315Thr mutation was prominent in Isoniazid mono-resistant strains (9/13) and in MDR strains (7/8). Three of 16 Isoniazid resistant strains with Ser315Thr mutation had an additional mutation in the regulatory region. No mutation were found in 6 of the 7 susceptible strains. Molecular methods in tuberculosis laboratory may improve detection of tuberculosis case with drug resistance case.   Key words:  Mycobacterium tuberculosis complex, susceptibility testing, resistant genes.