Molecular Characterization of Virulence Genes Associated with Salmonella spp. Isolated From Poultry

Abstract

Salmonella is still the major threat to the poultry industry and humans especially that of zoonotic importance. In the present study, a total of 300 samples (liver, intestine, yolk sac and spleen) collected from 100 broiler chickens were examined bacteriologically for the presence of Salmonella. The isolated salmonellae were then screened for virulence encoding genes using multiplex PCR and the antimicrobial susceptibility to antibiotics using disc diffusion method. Results showed that Salmonella was recovered from 5.33% of the examined samples. Sixteen Salmonella serovars were recovered [Salmonella Sinchem (n=3) Salmonella Typhimurium (n=2), Salmonella Gallinarum (n=2), Salmonella Enteritidis (n=2), Salmonella enterica subsp. Salamae (n=1), Salmonella Virchow (n=1), Salmonella Kentucky (n=2), Salmonella Heidelberg (n=1), Salmonella Farsta (n=1) and Salmonella Hydra (n=1)]. Results also showed that all the tested salmonellae (100%) were found harbor the virulence encoding gene specific amplicon of pagC, msgA, spiA, invA, prgH, orgA, sipB, tolC, iroN, lpfC, pefA, sitC, sifA, and sopB. While, only 30% and 70% of the examined salmonellae were harbor cdtB and spvB, respectively. The antimicrobial susceptibility testing of the isolates revealed that most of the isolated Salmonella serovars were expressed multiple antibiotic resistance indexes (MAR) to amoxicillin, doxycycline, chloramphenicol, ampicillin, gentamicin, trimethoprim/sulphamethoxazole. In conclusion, the results of the current study demonstrated that Salmonella isolated from broilers chicken were found to harbor many virulence encoding genes and expressed a high degree of MDR to antibiotics commonly used in human medicine.