**2. Nomenclature**

The first mention of the word "Enterococci" came up in 1899, when Thiercelin and Jouhad discovered a diplococcus from the human intestine and named it as


#### **Table 1.**

*Enterococcal species pathogenic to man.*

"enterococque" to describe its habitat. However, he was overruled by Andrews and Horder in 1906 who included enterococci in the genus streptococci based on their gram reaction, shape and ability to form chains in some circumstances. This continued till 1968, when Kalina questioned the inclusion. Kalina looked at the position of the Group D antigen and found it to be located inside the cell wall unlike the Group A antigen of streptococci. He found that culture is more diffuse in broth and spreading on solid media, chain formation occurred only in adverse physiological conditions and the natural arrangement was in pairs in broth culture. It did not display many of the virulence factors common to streptococci, like hyaluronidase. They called for changing the type species to *Enterococcus faecalis* and adding one more species to the genus, namely *Enterococcus faecium* which differed from the type species in not fermenting Mannitol. The basionym of the species was declared by them to be *Streptococcus faecalis* [1].

In 1984, Schliefer and Kilpper-Balz came out with the full justification for a separate genus for Enterococci. They showed that *E. faecalis* and *E. faecium* had less than 10% DNA homology with their closest species among streptococci, namely *S. bovis* and *Streptococcus lactis*, which came under Group D streptococci, having the same Lancefield grouping based on the cell wall polysaccharide [2].

In April 1984, the same researchers came up with a proposal to include "*S. avium*," "*S. casseliflavus*," "*Streptococcus durans*," "*S. faecalis subsp. malodoratus*," and *S. gallinarum* in the genus Enterococcus as distinct species [3].

At present there are 18 species pathogenic to human beings, under the genus *Enterococcus* (**Table 1**) [4].
