Multilocus sequence typing (MLST) is a genotypic method proposed in 1998 for classifying and subtyping bacterial populations. It identifies allelic variants in housekeeping genes, typically 7 genes that are amplified by PCR and sequenced. Each difference in the nucleotide sequences is assigned an allele number, and the combination of allele numbers across all genes defines the strain's sequence type. Strains with identical sequences for all genes have the same sequence type.

1. Multilocus Sequence Typing
(MLST)

2. What is MLST??
 Proposed by Maiden et al in 1998.
 Popular genotypic method in taxonomy classification.
 Identifies allelic variants to characterize, subtype and classify the
emembers of haploid bacterial population.
 Typing method for diploid organisms when adapted to HiMLST.

3. Procedure of MLST
 Consist of sequencing several different housekeeping genes (generally 7) fom an organism and
comparing there sequences with the sequences of the same genes from different strains of the
same orgaism.
 For each gene, an approximately 45-500 bp sequence is amplified using PCR and then
sequenced by Sanger’s mthod.
 Each nucleotide along the sequence arecompared and differenes are noted.
 Each differenceor sequence variant is called allele and is assigned a number. The strain being
studied is then assigned a series of numbers as its allelic profile or multilocus sequence types.
 Strains with identical sequences for a given gene have the same allele unde for that gene and
the two strains with identical sequences for all the genes have the same allelic profile.
 The relentless between each allelic profile is expressed in a dendrogram of linkage distance that
vary from