Detection of salmonellae in hen eggs in Thailand

Two thousand four hundred and ninety eggs were collected from retail markets in 6 provinces and from laying hen farms in 3 provinces. Eggs were pooled in groups of 3 to obtain 830 samples for testing. Isolation of salmonellae was made from both egg shell and egg contents. Eggs from retail markets were contaminated with salmonellae on egg shells (13.2%) and in egg contents (3.9%). Three (0.4%) samples yield positive both on egg shells and in egg contents. Of the 86 samples from laying hen farms, salmonellae were found on egg shells and in egg contents, 3.5% and 1.2%, respectively. From the 134 strains tested, twenty-four serotypes were confirmed. Salmonella cerro, S. amsterdam and S. typhimurium were predominantly encountered, 4.8%, 4.3% and 1.4%, respectively. Only two samples were contaminated with S. enteritidis, one each from open market and laying hen farm, one on egg shells and the other in egg content respectively.