Molecular grouping of Listeria monocytogenes based on the sequence of the inIB gene.

The major part of the gene inlB was sequenced in 24 strains of Listeria monocytogenes belonging to serovars 1/2a, 1/2b, 1/2c, 3b and 4b. A phylogenetic analysis based on the inlB nucleotide sequences showed that strains of serovars 1/2a and 1/2c were closely related, as well as those of serovars 1/2b and 3b. Strains sharing serovar 4b could be divided into two distinct groups. There were differences in amino-acid sequence between all serovars except between serovars 1/2b and 3b. Differences in amino-acid sequence were also seen within each of the serovars 1/2a and 4b. The data presented indicate that the inlB gene may be useful for typing purposes as an alternative or complement to serotyping.