Emergence of lmonellaenterica subspecies enterica serovar in Iraqi broiler chiken farmsand humans

Abstract

Background: worldwide, many domestic and wild animals can serve as a reservoir and harboring various pathogens in their gastrointestinal tracts without exhibiting the signs of illness.

Aim:Isolation and molecular confimation of S. entericasubsp. entericain the fecal samples of broiler chicken farms and humans withphylogenetic analysis of some study isolates.

Materials and methods: Totally, 100 fecal samples were collected for the current study including 50 samples obtained from the broiler chicken farms located at different areas inAl-Qadisiyah province, and 50 stools from humans. Initially, all fecal samples were subjected to traditional isolation and biochemical identification of Salmonella sp.; and then, the positive isolates were subjected to molecular confirmation of S.entericaby the polymerase chain reaction (PCR). Finally, four molecularly positive isolates were selected randomly and sequenced to be submitted in the NCBI-GenBank and examined phylogenetically.

Results: Traditional culture and biochemical testing of totally 100 fecal samples revealed that 32% samples were positive, which comprises 30% of broiler chicken and 34% of human fecal samples. Targeting the 16S rRNA gene, the results of PCR assay detected that an overall prevalence rate of S.entericaamong 32 positive isolates was68.75% which identified in 66.67% of broiler chickens and 70.59% of human fecal samples. The sequence data of the 4 study isolates were submitted, named and get specific access numbers in the NCBI-GenBank database as SE-1 (OR563806.1), SE-2 (OR563807.1), SE-3 (OR563808.1), and SE-4 (OR563809.1). Then, multiple sequence alignment, phylogenetic tree analysis and homology sequence identity revealed that three of local study isolates (SE-1, SE-3 and SE-4) were identical to the S. entericasubsp. enterica Chinese (JF951183.1) and Iraqi (KP420235.1) isolates at a level of similarity ranged from 99.87% to 99.99% and a level of mutation ranged from 0.0001% to 0.0006%; while, the local study isolate SE-2 was identical to the S. entericaIranian (EU118116.1) isolate at 98.5% level of similarity and 0.0007 level of mutation.

Conclusion:This study revealed the high prevalence of S.enterica subsp. enterica in both chicken farms and humans indicating that control of infections remains a significant challenge as the pathogen demonstrated remarkable ability to adapt and persist in various environments. Therefore, this study suggests that improved biosecurity measures, enhanced food safety practices, and the judicious use of antimicrobials in animal production are all crucial components of a multifacted approach to mitigate the prevalence and impact of S. enterica.