Evaluation of phenotypic and molecular typing techniques for determining diversity in Erwinia carotovora subspp. atroseptica

A number of phenotypic and molecular fingerprinting techniques, including p hysiological profiling (Biolog), restriction fragment length polymorphism ( RFLP), enterobacterial repetitive intergenic consensus (ERIC) and a phage t yping system, were evaluated for their ability to differentiate between 60 strains of Erwinia carotovora ssp. atroseptica (Eca) from eight west Europe an countries. These techniques were compared with other fingerprinting tech niques, random amplified polymorphic DNA (RAPD) and Ouchterlony double diff usion (ODD), previously used to type this pathogen. Where possible, data we re represented as dendrograms and groups/subgroups of strains identified. S impson's index of diversity (Simpson's D) was used to compare groupings obt ained with the different techniques which, with the exception of Biolog, ga ve values of 0.46 (RFLP), 0.39 (ERIC), 0.83 (phage typng), 0.82 (RAPD) and 0.26 (ODD). Of the techniques tested, phage typing showed the highest level of diversity within Eca, and this technique will now form the basis of stu dies into the epidemiology of blackleg disease.