A SALMONELLA-SPECIFIC DNA-PROBE AND ITS USE IN SOUTHERN HYBRIDIZATIONFOR DIFFERENTIATION OF SALMONELLA-ENTERITIDIS

Chromosomal DNA from phage type 13a and Phage type 8 of Salmonella ent eritidis (SE) was cloned in Escherichia coli using the plasmid pUC8. A 2.1-kilobase-pair (kbp) DNA fragment specific for Salmonella spp. was identified by colony, dot, and Southern hybridization analyses. When labeled and used as a probe (C7) this recombinant clone hybridized wit h the DNA of 18 Salmonella species hut did not hybridize with the DNA of seven other enteric and non-enteric bacterial species. In Southern blot hybridization, this probe hybridized specifically to a 6.0-kbp Bg /I digested DNA fragment of 17 SE isolates from human as well as avian sources, thus differentiating this fragment from DNA of 17 other Salm onella species. The C7 probe also hybridized to a 5-kbp fragment of on e SE DNA derived from human and two SE DNA from poultry sources. This may indicate variation among SE isolates.