Molecular tools for typing and branding the tubercle bacillus

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Variable genetic sequences have enabled molecular typing of Mycobacterium tuberculosis complex (MTC) organisms for two decades.
• Genome sequencing of M. tuberculosis and M. bovis has clarified the nature of these variable sequences, guiding the selection of molecular typing tools.

Purpose of the Study:

• To review classical genotyping methods for molecular epidemiology.
• To detail post-genomic typing methods, focusing on genomic deletions as lineage-specific markers.

Main Methods:

• Review of established genotyping techniques.
• Detailed analysis of large sequence polymorphisms (genomic deletions) for bacterial lineage identification.

Main Results:

• Genomic deletions are unique, non-revertible polymorphisms that effectively 'brand' bacterial lineages.
• These deletions allow for precise classification of MTC species, sub-species, and M. tuberculosis sensu stricto clades.

Conclusions:

• Genomic deletions represent a significant advancement in classifying MTC organisms.
• This method offers new opportunities for accurate diagnostics and epidemiology.
• Genomic deletions provide a foundation for studying natural variability within MTC organisms.