Purpose: Since there were no specific data on Salmonella prevalence on egg products in Korea, we investigated the Salmonella contamination of eggs and liquid whole eggs from an egg-breaking plant.
Methods: We collected 800 eggs, and 40 unpasteurized and 30 pasteurized liquid whole egg samples from eight egg-breaking plants in spring, summer and winter during 2011. Samples were incubated with 225 ml buffer peptone water (BPW) solution by adding 25 ml shell egg pools (20 eggs), 25 ml unpasteurized and pasteurized whole liquid eggs. After 1 ml and 0.1 ml incubated BPW solutions were transferred 10 ml tetrathionate broth and 10 ml rappaport vassiliadis broth, respectively, they were incubated at 36 °C, 42 °C during 24 hours. The two incubated solutions were streaked on xylose lysine desoxycholate (XLD) agar. Colonies suspected to be Salmonella were confirmed by PCR and VITEK. The gene diversity of isolates was investigated by Rep-PCR.
Results: Salmonella weren't detected on eggs, unpasteurized and pasteurized liquid whole eggs collected in spring and winter. In contrast, Salmonella were detected in four unpasteurized liquid whole eggs from 2 egg-breaking plants (A and B) and Salmonella were detected in five pasteurized liquid whole eggs from only one egg-breaking plant (A) collected in summer. Seven of Salmonella isolates from A plant were all S. Bareilly which showed above 95% similarity. S. Bareilly from feces of farm that supplied eggs to plant was isolated and they showed 95% similarity with it from liquid whole egg. Two of Salmonella isolates from B plant were S. Bareilly and S. Richmond.
Significance: Salmonella spp. were isolated for the first time from pasteurized and unpasteurized liquid whole egg collected in summer two egg-breaking plants in Korea.