Molecular typing of Salmonella enterica subsp. enterica serovar Enteritidis isolates

A collection of 31 epidemiologically unrelated Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) isolates obtained during a 12-year period was characterised by different molecular typing methods. Plasmid profile analysis, the detection of plasmid-encoded virulence genes and ribotyping allowed little or no further differentiation amongst these isolates. Two different hybridisation patterns were observed by IS200-typing of the S. Enteritidis isolates. However, pulsed-field gel electrophoretic separation of restriction endonuclease-digested whole-cell DNA provided a high level of discrimination amongst the 31 S. Enteritidis isolates. This could be increased by the comparative use of the three suitable restriction endonucleases XbaI, 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 represents a most helpful tool for the epidemiological typing of S. Enteritidis isolates.