Leptospira taxonomy: then and now

The genus Leptospira, isolated for the first time in 1915, is one of the most diverse genera of bacteria which includes species isolated worldwide. The first taxonomic classification was based on the serological similarities of the strains. The basic taxon in the serological classification is serovar. More than 300 serovars are currently known. Furthermore, for many years the genus was divided into two species, the saprophytic Leptospira biflexa and the pathogenic Leptospira interrogans. The introduction of genetic techniques has led to a new species classification. In this review, we described the changes that have taken place over more than a century in the classification system of these bacteria and present the current state of the taxonomy of the genus Leptospira based on genome analysis. A complete list of the currently recognize 68 species of the genus Leptospira is presented, together with their phylogenetic relationships reflecting virulence status.