Molecular typing of Salmonella enterica subsp. enterica serovar Enteritidis Isolates

A total of thirty-one epidemiologically unrelated Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) isolates obtained during a twelve-year-period were characterized by different molecular typing methods. Plasmid profile analysis, the detection of plasmid-encoded virulence genes as well as ribotyping allowed little or no further differentiation among these isolates. Two different hybridizaiton patterns could be observed by IS200-typing of the S. Enteritidis isolates. However, pulsed-field gel electrophoretic separation of restriction endonuclease digested whole cellular DNA provided a high level of discrimination among the 31 S. Enteritidis isolates. This could be increased by the comparative use of the three suitable restriction endonucleases Xbal, SpeI and NotI. Thus, pulsed-field gel electrophoresis proved to be superior in its discriminatory value to other molecular methods such as plasmid analysis, ribotyping or IS200-typing and might represent a most helpful tool for the epidemiological typing of S. Enteritidis isolates.