12 - From Multilocus Enzyme Electrophoresis to Multilocus Sequence Typing

Abstract

Multilocus Enzyme Electrophoresis (MEE) and Multilocus Sequence Typing (MLST) is a powerful new approach for the characterization of microorganisms, because it provides unambiguous molecular typing data that are electronically portable between laboratories, and that can be used in studies of global epidemiology. The technique is based on the analysis of electrophoretic variation in a set of chromosomally encoded cytoplasmic enzymes. For several species of bacteria, the genetic relationships obtained by MEE have been shown to be strongly correlated with those obtained from DNA-DNA hybridisation analysis. MLST schemes for Staph. aureus, Strep. pyogenes, H. influenzae, Yersinia spp., and other major pathogens are under development. MLST is a simple technique that requires only the ability to amplify specific DNA fragments by PCR and to sequence those fragments. While the method is still quite expensive, further technological developments in automated sequencing should soon render MLST accessible to all major public health laboratories, including those in the developing world. In line with the impact of MEE, MLST will further improve the understanding of the population and evolutionary biology of microbial pathogens, as well as other microorganisms. For the more stable microbial pathogens, sequence analysis of one or a few hypervariable loci, in addition to the MLST scheme based on housekeeping genes, will provide a versatile tool for studies of both global and local epidemiology.