Background: M. leprae was presumed as an aetiologic agent in DLL, without specific microbiologic studios in the past. The sequencing of the genome through genetic testing led to the discovery of a new species M. lepromatosis by Han et al. in 2008.
Materials and methods: The genetic analysis of the phylogeny of bacteria, based on the analysis of the 16S rRNA coding regions and other genes (eg, rpoB, rpoT, hsp65, mmaA, fibF-rpsO) appears to be helpful in species discrimination. Twenty genes and pseudogenes (22,818 bp of sequence) proved that in the phylogenetic tree M. leprae and M. lepromatosis are closely related. On the other hand, the differences were great, which gave rise to the distinction between the two species. Detected insertions in both species of mycobacteria in the rRNA and mmaA genes were similar to each other and were found only in the human genome, which confirms the close relationship during M. leprae and M. lepromatosis evolution of genomes in the human species.
Results: The first population-based study analysing the presence of both mycobacteria indicates that M. lepromatosis came to America with human populations migrating from Asia through the Strait of Bering, in contrast to M. leprae, which came to America with the colonists and as a result of the slave trade.
Conclusions: The latest experiments with M. lepromatosis showed that it is a specific agent in DLL, not only in the endemic area in Mexico, but also in different parts of the world. M. lepromatosis was also found in other forms of multibacillary leprosy, or as a dual infection with M. leprae, as well. There are great expectations that genetic methods with the sequencing of the whole genome will lead to a better understanding of some of the mysteries behind leprosy.