Discrimination of Listeria monocytogenes by Sequence Typing Based on Two Housekeeping Genes and Its Comparison to PFGE Patterns

Two housekeeping genes, of Listeria monocytogenes dat and hlyA, were analyzed in a set of 28 isolates from different sources to estimate their genetic diversities. These strains were previously characterized by pulsed-field gel electrophoresis. Complete gene sequences for dat (465 bp) and hlyA (584 bp) had sequence similarity of $99.87-100\%$ S and $99.96-100\%$ S among isolates, respectively. Also, we found that the numbers of sequence types (ST) were about 3-fold less than those of PFGE types (3 STs versus 11 PFGE types). There was, however, a good correlation between the PFGE patterns and phylogenetic grouping of two gene sequences among the isolates. Further studies on analyzing additional loci would increase the discriminatory power of sequence typing for L. monocytogenes strains.