An epidemiological analysis of Salmonella enteritidis contamination in a rat-infested chicken layer farm, an egg processing facility, and liquid egg samples by pulsed-field gel electrophoresis

In order to determine the epidemiological link between the Salmonella Enteritidis contamination in a rat-infested chicken layer farm, an attached egg processing facility and liquid egg samples, several S. Enteritidis isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and bacteriophage typing. A total of 33 S. Enteritidis strains were isolated from a total of 4,081 samples. Similar pulsed-field patterns were generated by S. Enteritidis isolates from liquid eggs, rats and effluent water. Additionally, only two phage types were detected among the S. Enteritidis isolates, PT 1b and PT 6. These results suggest that S. Enteritidis isolates from rats, egg processing facility, and liquid eggs are genetically related. Furthermore, S. Enteritidis infection in rats in layer farms poses a serious public health concern and should be included in future epidemiological studies.