**1. Introduction**

Salmonellae are gram-negative bacteria and members of the family Enterobacteriales. They are chiefly intestinal parasites of human and a wide variety of animals including wild birds, domestic pets, rodents, chickens etc. They are also found in sewage, rivers and waters and soil. The genus *Salmonella* is divided into two species: *Salmonella enterica* that encompasses six subspecies (I, II, IIIa, IIIb, IV, and VI), and *Salmonella bongori*, which was earlier subspecies V [1]. Members of the seven *Salmonella* species can be serotyped into more than 2500 serotypes (serovars) based on somatic O and H antigens [1].
