[Tuberculosis focused through the molecular biology zoom].

The sequence of Mycobacterium tuberculosis genome set up a process of systematic research and improved the understanding of the microorganism biology, albeit the clues of its virulence and pathogenicity still remain rather cryptic. Genetic engineering did not succeed in designing more effective or convenient tools to accomplish the control of tuberculosis. Neither the bacillus variants created by mutagenesis and recombination nor the microorganism subunits (antigens, DNA) proved to be significantly better than the BCG vaccine as immunogens. Likewise, the search for novel bacterial targets and more active antibiotics has been unfruitful thus far, even though some advance in drugs formula or delivery systems is in progress. Conversely, new and ingenious instruments have been developed to optimize the epidemiological tracing and diagnosis of the disease. The finding of strain molecular markers consolidated the investigation of tuberculosis spread and revealed the expansion and prevalence of certain lineages of the bacillus in some ecological niches. Molecular methods are specific to immediately characterize the bacilli detected by microscopy or culture which resulted in rapid diagnosis build-up. This improvement is decisive for immunodepressed patients and those affected by multidrug-resistant tuberculosis. To be meaningful and precise the results produced by molecular investigations must be properly backed up by conventional microbiology, pathology and epidemiology.