DISCRIMINATION OF LISTERIA-MONOCYTOGENES STRAINS OF SEROTYPE 4B BY RESTRICTION ENZYME ANALYSIS OF CHROMOSOMAL DNA

Epidemiologically related cheese and environmental strains and epidemi ologically unrelated strains of Listeria monocytogenes serotype 4b wer e examined by restriction enzyme analysis of chromosomal DNA with a to tal of 10 restriction enzymes. The DNA fingerprint patterns generated from each restriction enzyme digest of total DNA of all strains were c lassified. The restriction enzyme patterns of seven strains recovered from cheese and environmental samples in the same plant were identical to each other, but differed from those of seven epidemiologically unr elated strains. Two, originating from sporadic human patients, of eigh t epidemiologically unrelated strains exhibited the identical restrict ion enzyme patterns. Excepting these two strains, restriction enzyme a nalysis of the chromosomal DNA of L. monocytogenes serotype 4b can dis criminate serologically indistinguishable strains.