Isolation, identification and characterization of Salmonella enteritis from Yunnan laying hens

Abstract:

[Background] Salmonella enteritis is an important zoonotic pathogenic bacterium that is transmitted essentially by poultry meat products and eggs. [Objective] In order to confirm pathogen information in a breeder farm where the poultry was suspected to be infected by Salmonella in Yunnan province. [Methods] we collected liver tissues from infected chicken in sterile environment to isolate and culture bacteria, then performed drug sensitive test and pathogenicity test, as well as identification of virulence genes for obtained strain. [Results] The isolated bacterium was identified to be Salmonella enteritidis and named SSYN001. Its antigen structural formula consists of the O antigen 1(+), 9(+), 12(+), H antigen gm(+) and [1,7](+). Drug resistance assay suggests that this strain was resistant to penicillin, bactrim, doxycycline and tetracycline, but sensitive to 8 antibiotics, include amoxicillin, ampicillin, gentamicin, tobramycin and ceftazidime. By detecting its resistance gene, we found that the strain contains tetA, a tetracycline resistance gene. The pathogenicity test shows the lethality of this strain for chicks, layer chicken and mice was 40%, 80% and 100%, respectively; eventually, we found this bacterium has 15 virulence genes consisted of spvB, spiA, pagC, msgA, invA, sipB, prgH, spaN, tolC, iroN, sitC, lpfC, sifA, sopB and orgA. [Conclusion] The present study provides new data of the pathogenicity of laying hen’s Salmonella enteritidis in Yunnan province, with implication for public health on detection of foodborne zoonotic Salmonella.