Diversity of strains of Salmonella enterica serotype enteritidis from English poultry farms assessed by multiple genetic fingerprinting

Reliable and sufficiently discriminative methods are needed for differentia ting individual strains of Salmonella enterica serotype Enteritidis beyond the phenotypic level; however, a consensus has not been reached as to which molecular method is best suited for this purpose. In addition, data are la cking on the molecular fingerprinting of serotype Enteritidis from poultry environments in the United Kingdom. This study evaluated the combined use o f classical methods (phage typing) with three well-established molecular me thods (ribotyping, macrorestriction analysis of genomic DNA, and plasmid pr ofiling) in the assessment of diversity within 104 isolates of serotype Ent eritidis from eight unaffiliated poultry farms in England. The most sensiti ve technique for identifying polymorphism was PstI-SphII ribotyping, distin guishing a total of 22 patterns, 10 of which were found among phage type 4 isolates. Pulsed-field gel electrophoresis of XhaI-digested genomic DNA seg regated the isolates into only six types with minor differences between the m. In addition, 14 plasmid profiles were found among this population. When all of the typing methods were combined, 54 types of strains were different iated, and most of the poultry farms presented a variety of strains, which suggests that serotype Enteritidis organisms representing different genomic groups are circulating in England. In conclusion, geographical and animal origins of Salmonella serotype Enteritidis isolates may have a considerable influence on selecting the best typing strategy for individual programs, a nd a single method cannot be relied on for discriminating between strains.