Exploring the traits, genetic variability and antibiotic resistance of salmonella serovars in poultry farming in Pakistan

Salmonellosis in poultry have been reported worldwide as the major cause of gastrointestinal foodborne illness and unembellished losses to the poultry industry. The current study aimed to isolate, purify, and characterize the species in suspected chickens during natural outbreaks in commercial poultry farms in Pakistan. A total of 50 dead birds were randomly selected and examined for postmortem from each of the 10 farms located in different areas of Punjab and Sind provinces of Pakistan. Liver and cloacal swab samples from each of the birds showing typical lesions were collected and inoculated on Salmonella-shigella agar (SSA), Xylose-Lysine deoxycholate agar (XLD) and CHROM agar (CA). The DNA of the isolates was extracted and amplified using an flhB gene specifically designed primer for Salmonella. The gene sequences of the different isolates were analyzed using the NCBI portal and a phylogenetic relationship was established (DNA-Star version 2.0). Small black center colonies with translucent margins appeared after 24 hours of incubation at 37°C, showing a 379bp PCR product. The validated sequences were deposited in the NCBI database with accession numbers PP393497 through PP726904. Gene sequence analysis revealed two different serovars of Salmonella species (13%) and (80%) while the remaining isolates did not predict any similarity to the NCBI database. The isolates showing more than 99% similarity to accession numbers are CP011365, CP129209, CP011365, CP129206, CP011365, CP011365, CP011365, CP129206, CP011942, CP129209, CP129206, CP129209, LR792395and CP100724. Finally, most gram-negative bacteria are sensitive erythromycin, and tetracycline, and they also showed resistant to ofloxacin and gentamycin.