Whole genome sequencing of isogenic collection of antibiotic-resistant Mycobacterium tuberculosis strains. Mycobacterium tuberculosis subsp. tuberculosis

We analysed the genomes of 13 isogenic drug-resistant Mycobacterium tuberculosis laboratory strains to investigate the emergence of additional non-resistance associated genetic changes, possibly indicating adaptive evolution. We observed the fixation of multiple mutations, some of which could already be identified as minority variants in the culture of the susceptible parent strain. These results show that bacterial populations presumed homogeneous can be in fact genetically diverse and that low frequency variants can be fixed in the genome during subsequent bottlenecks.