Salmonella isolation from poultry sources
During April 1-October 30, 2019, a total of 293 samples were collected and tested for Salmonella Enteritidis (230 from retail chicken meats, 31 from internal organs of chicken, and 32 from straw bedding samples from geographically seperated multiple poultry farms) were aseptically placed in a sterile plastic bag containing 400 mL of buffered peptone water broth (BPW, Difco, Detroit, MI, USA) and shaken for 2 min. The rinsed material (20 mL) was vortex-mixed in 20 mL of BPW for 15 s, and then incubated at 37°C for 24 h. Incubated BPW (100 µL) was vortex-mixed for 15 s in 10 mL of Rappaport-Vassiliadis broth, then incubated at 41.5°C for 20 h. The presence of Salmonella spp . in the incubated Rappaport-Vassiliadis broth was analysed by PCR as described previously . Samples that yielded positive results in PCR analysis were streaked onto the Salmonella ChromoSelect agar (Sigma-Aldrich, USA), followed by incubation at 37°C for 24 h. The pink colonies of Salmonella spp. on the agar were validated by PCR and positive colonies were stored at -80°C in glycerol.