Discrimination of Listeria monocytogenes strains of serotype 4b by restriction enzyme analysis of chromosomal DNA.

Epidemiologically related cheese and environmental strains and epidemiologically unrelated strains of Listeria monocytogenes serotype 4b were examined by restriction enzyme analysis of chromosomal DNA with a total of 10 restriction enzymes. The DNA fingerprint patterns generated from each restriction enzyme digest of total DNA of all strains were classified. 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 unrelated strains. Two, originating from sporadic human patients, of eight epidemiologically unrelated strains exhibited the identical restriction enzyme patterns. Excepting these two strains, restriction enzyme analysis of the chromosomal DNA of L. monocytogenes serotype 4b can discriminate serologically indistinguishable strains.