SUBTYPING OF A FREQUENT PHAGOVAR OF LISTER MONOCYTOGENES IN SWEDEN BYUSE OF RESTRICTION-ENDONUCLEASE ANALYSIS

In Sweden, many Listeria monocytogenes strains belonging to serovar 4b and isolated during the last five years from different sources share the same phagovar - 2389:2425:3274:2671:47:108:340. The object of the present study was to investigate if 31 L. monocytogenes serovar 4b str ains belonging to this particular phagovar could be differentiated by use of a simple restriction endonuclease analysis (REA). Among the enz ymes tested, Xho I was found to be the most useful, since this enzyme could divide the 31 strains into five groups. The profiles of all huma n clinical isolates were indistinguishable from each other, which indi cates that these strains may represent a single clone. The food isolat es and the strains of human origin did not share the same profile. Thi s further characterization may be of epidemiological importance as thi s phagovar of L. monocytogenes has been associated with at least two o utbreaks of human listeriosis in Europe.