Occurrence, virulence, and resistance genes in Salmonella enterica isolated from an integrated poultry company in Jordan

Salmonella is considered one of the most common foodborne pathogens worldwide. The annual number of hospitalizations and deaths related to zoonotic salmonellosis, which is transmitted from animals to humans and infects poultry and meat, is expected to be significant. Hence, the primary aims of this research were to isolate and characterize Salmonella species obtained from an integrated poultry company and identify some virulence, and antimicrobial resistance, with a specific concern about colistin resistance genes. A total of 635 samples collected from various sources in an integrated company in Jordan were screened for Salmonella species accompanying their virulence and antimicrobial resistance genes. Samples were collected from parent stock house drag swabs, broiler farms, premix, cecum at the slaughterhouse level, pre-chilling and post-chilling stages, and the final product. Salmonella species were detected in 3% (6\200) of investigated parent stock house drag swabs, 13.8% (11/80) from cloacal swabs from broiler farms, 16.9% (11/65) from boiler farms premix, 24.4% (11/45) from the cecum at slaughterhouse level, 16.4% (9/55) from the pre-chilling stage, 37.8% (17/45) from the post-chilling stage and 53.3% (24/45) from the final product stage. No isolates were detected in feed mills (0/20), parents' premix (0/40), or hatcheries (0/40). Salmonella isolates were resistant to ciprofloxacin (91.0%), nalidixic acid (86.5%), doxycycline (83.1%), tetracycline (83.1%), sulphamethoxazole-trimethoprim (79.8%) and ampicillin (76.4%). Serotyping shows that S. Infantis was the predominant serovar, with 56.2%. Based on the minimum inhibitory concentration (MIC) test, 39.3% (35/89) of the isolates were resistant to colistin; however, no mcr genes were detected. Among antimicrobial-resistant genes, blaTEM was the most prevalent (88.8%). Furthermore, the spvC, ompA, and ompF virulence genes showed the highest percentages (97.8%, 97.8%, and 96.6%, respectively). In conclusion, Salmonella isolates were found at various stages in the integrated company. S. Infantis was the most prevalent serotype. No mcr genes were detected. Cross-contamination between poultry production stages highlights the importance of good hygiene practices. Furthermore, the presence of virulence genes and the patterns of antimicrobial resistance present significant challenges for public health.