Why is there now only one Salmonella species?

Question

Once upon a time, I chanced upon an old microbiology book that detailed the rather colorful world of enterobacteria. *Salmonella* in particular stood out, as it seemed there were a lot of species: typhi / typhosa, paratyphi, gallinarum, typhimurium, choleraesuis, and quite a bunch of others that I have now forgotten. Flipping through a newer book, it now seems that all of these "species" were collated under choleraesuis (and now more recently *enterica*), with all those species being demoted to "strains" (or maybe I should use the current term of art, "serovar"). Unfortunately, the book didn't give much in the way of explaining about this merger. So, why is there now only S. enterica? If S. typhi" is a mere serovar, how come the species name is still used in the literature?

Answer 1

Like many organisms, they started out being named for the host they infect or location of isolation. Advances in molecular biology helped us eventually distinguish between species, subspecies and serotype, etc. It was discovered that Salmonella is actually just two species - bongori is the other one (as far as we know). Names often stick even if the classification changes. Just another example of how technological advances and a long course of study help us to better understand the world around us.