Our MLST is an unambiguous procedure for characterizing isolates of bacterial species using the sequences of internal fragments of (usually) 6 to 8 house-keeping genes. Approximately 450-500 bp internal fragments of each gene are used, as these can be accurately sequenced on both strands. For each of these housekeeping genes, the different sequences are assigned as alleles and the alleles at the loci provide an allelic profile or sequence type (ST). A series of profiles can then be the identification marker for strain typing.
The great advantage of MLST is that sequence data are unambiguous and the allelic profiles of isolates can easily be compared to those in a large central database via the internet. A further advantage of MLST is that the profiles can be obtained from clinical material directly from CSF or blood. Thus isolates can be precisely characterized even when they cannot be cultured from clinical material. The common microorganisms tested in our laboratory include Cronobacter spp, Bacillus cereus, Bacillus licheniformis, Escherichia coli, Listeria monocytogenes, Propionibacterium acnes, Salmonella enterica and Staphylococcos aureus.