Typing of Salmonella enterica subsp. enterica serovars Choleraesuis, Typhimurium, Dublin and laboratory strains of Escherichia coli using subtracted restriction fingerprinting (SRF).

The aim of the present study was to evaluate the usefulness of a new typing technique called subtracted restriction fingerprinting (SRF) for bacterial strain and isolate discrimination. The technique was applied to isolates of Salmonella enterica subsp. enterica (S.) serovars Choleraesuis, Typhimurium, Dublin and to two laboratory strains of E. coli. SRF is based on the selective removal of excess fragments from a restriction digest using magnetic particles. Subsequently, the remaining subset of restriction fragments can easily be analyzed with a conventional agarose gel. Larger fragments are preferentially removed by SRF. This results in an even distribution of bands within each electrophoretic lane and significantly improves scoring. The high discriminatory index for (S.) Choleraesuis (D = 0.914) illustrated the suitability of SRF for genome typing.