ABSTRACT
Salmonellosis is one of the most important zoonotic diseases throughout the world. The purpose of this study was to characterize a large collection of Salmonella isolates from different poultry sources in Iran. A total of 123 Salmonella isolates from different poultry sources were subjected to drug susceptibility test, hemolysin production, motility test, and plasmid profile [50 isolates]. Seventy-one resistance patterns were found to 29 antimicrobial agents among 123 Salmonella isolates, in which 81% of isolates were resistant to more than one antibacterial agent. The resistance patterns of 123 isolates to 10 commonly used antibacterials in Iranian poultry industry were also quite variable and included 31 patterns. Four different plasmid patterns were found among 50 Salmonella isolates. Fifty four percent of Salmonella isolates harbored one or three plasmids with approximate molecular size ranging from 2.3 to 68 kb. No plasmid was detected in 46% of isolates. A band of 68 kb size was detected in all isolates that harbored plasmid. All isolates were motile but no isolate showed hemolysin production. The frequency of resistance to antibacterial agents among avian Salmonella isolates is a major public health concern