The degree of Salmonella gallinarum contamination in industrial poultry farms in the northwest of Iran and the pattern of antibiotic resistance and the frequency of some virulence genes

Gallinarum disease caused by Salmonella gallinarum is one of the most challenging diseases in the poultry industry. In this study, the level of Salmonella gallinarum contamination of industrial chicken flocks in northwestern Iran, antibiotic resistance and frequency of some virulence genes (msgA, spiA, pagC) were investigated and evaluated. All the samples taken from the herds with suspected clinical symptoms of salmonellosis from the clinics of East Azarbaijan, West Azarbaijan, Ardabil and Zanjan provinces were examined and confirmed by microbial culture, chemical analysis, PCR and serological methods. After confirming the diagnosis of involvement with Salmonella gallinarum, antibiotic resistance was evaluated by disking method and the abundance of virulence genes in each isolate was checked. Of the 25 isolates of Salmonella gallinarum in this study, the highest microbial resistance was reported to tetracycline (76%), oxytetracycline (72%) and the highest sensitivity to amikacin (80%) and Fozbek (72%). 100% of the isolates were resistant to at least 6 types of antibiotics. In the study of the isolates, 8% had the msgA gene, 28% had the spiA gene, and 8% had the pagC gene, of which two isolates had all three virulence genes.