Pulsed-field gel electrophoresis as a molecular tool for characterizing genomes of certain food-borne bacterial isolates - a review

The evolutionary transition from phenotypic to molecular analysis of infectious disease in bacterial epidemiology led to the search for suitable approaches to ascertain genomic relatedness or heterogeneity between bacterial clinical isolates. Pulsed-field gel electrophoresis (PFGE) technique was developed for separating and analyzing long DNA fragments of several megabases in alternating electric field. Comparison of electrophoresis profiles of restriction enzyme-digested genomic DNA from bacterial isolates has proved to be a useful epidemiological tool for genetic discrimination of bacterial strains, detection of genetic relatedness, to locate the source of outbreak and to monitor the spread of the microorganisms in endemic zones. PFGE is considered as a gold standard method for typing of bacterial isolates because of the remarkable endurance of this technique as a typing method for the last 20 years in molecular epidemiology. In this current review the pros and cons of PFGE use in current molecular microbiological research are explored in the context of determination of genome organization of certain food-borne bacterial isolates causing infectious diseases in human beings.