Assessment of Salmonella spp. in feces, cloacal swabs, and eggs (eggshell and content separately) from a laying hen farm

Microbial pathogens of the genus Salmonella are among the leading causes of foodborne illness in the world. The present study was done on a laying hen farm with a Salmonella enterica serovar Enteritidis-positive result according to the testing specified by European regulation 2160/2003. The aim of this study was to compare the Salmonella contamination on a laying hen farm with the Salmonella presence in the hen eggs. The strains were isolated by ISO method 6579:2002 (standard method for the detection of Salmonella spp. in the European regulation for food and animal feeding stuffs, animal feces, and environmental samples from the primary production stage, including poultry farms) and were confirmed as Salmonella Enteritidis by the Kauffmann-White method. In addition, strains were compared with genomic macrorestriction followed by pulsed-field gel electrophoresis. Four types of samples, namely, feces (n = 50), cloacal swabs (n = 150), eggshells (n = 50), and egg contents (n = 50), were taken from each of 50 randomly selected battery cages. Results demonstrated that feces (92%) were the most positive sample, followed by eggshells (34%) and cloacal swabs (4%). No Salmonella spp. were detected in the egg contents. Our results show that a Salmonella Enteritidis-positive result on a laying hen farm, according to the testing specified by European regulation 2160/2003, did not imply the presence of the pathogen in the egg contents. Additionally, XbaI-digested genomic DNA of Salmonella Enteritidis strains isolated from several samples resulted in the same pattern, so were probably of the same origin.