MOLECULAR TYPING OF SALMONELLA-ENTERICA SUBSP ENTERICA SEROVAR HADAR - EVALUATION AND APPLICATION OF DIFFERENT TYPING METHODS

A highly discriminatory molecular typing system for isolates of Salmon ella enterica subsp. enterica (S.) serovar Hadar was developed based o n the data obtained from 34 epidemiologically unrelated S. Hadar isola tes from Germany and Brazil. Plasmid profile analysis and macrorestric tion analysis with the enzymes XbaI, SpeI and BlnI represented the mos t discriminative typing methods. In contrast, ribotyping as performed with a gene probe that recognized the entire rrn operon did not reveal any differences between the S. Hadar isolates. IS200 typing was not a pplicable due to the lack of insertion elements of this type in all S. Hadar isolates included in this study. The combination of the results of plasmid analysis and macrorestriction analysis subdivided the 34 S . Hadar isolates into 32 different genomic groups. The high discrimina tory power of these methods confirmed their suitability as effective t yping methods for epidemiological studies on S. Hadar isolates. The pr actical application of this molecular typing system to S. Hadar isolat es of the same flock obtained during a 15 month period strongly sugges ted recurring introduction of genomically different S. Hadar isolates instead of a single introduction of S. Hadar followed by subsequent sp read within the flock. (C) 1998 Elsevier Science B.V.