**3.** *Salmonella* **nomenclature, taxonomy and serovars**

*The nomenclature system of Salmonella* is a complex process. This genus is composed of two main species, *S*almonella enterica and *Salmonella bongori. Salmonella enteric* is further divided into 06 subspecies on the basis of biochemical properties and genomic relatedness [24]. The subspecies are denoted by Roman numerals: I. *S. enterica* subsp. *enterica*; II. *S. enterica* subsp. *salamae*; III. *S. enterica* subsp. *arizonae*; IIIa. *S. enterica* subsp. *diarizonae*; IV. *S. enterica* subsp. *houtenae*; V. *S. enterica* subsp. *indica*. The *S. enterica* subsp. *enterica* (I) is most common subspecies of *Salmonella* and is found to be predominantly associated with around 99% of *Salmonella* infections in humans & warm blooded animals. The remaining 05 subspecies and *S. bongori* are mainly attributed to *Salmonella* infections in cold blooded animals and are rarely found in humans [25].

For serotypes in subspecies (I), CDC uses names i.e. Enteritidis, Typhimurium, Choleraesuis and Typhi while as for the unnamed serotypes described post 1966 antigenic formulae are used in subspecies II, IV, VI and *S. bongori*. The name generally refers to the location (geographic) where the serovar/serotype was isolated first. In order to avoid any confusion between species and serotype, the first letter of the named serotype is written in capital and is not italicized. At the first citation of a serotype, the genus name is given first, followed by the word "serotype" or abbreviated form "ser" and finally the serotype name is written. One of the examples is *Salmonella* serotype or ser. Typhimurium. Afterwards the genus name can be directly written followed by serotype name (e.g. *Salmonella Typhimurium* or *S. Typhimurium* [26, 27].
