Pulsed-Field Gel Electrophoresis As a Molecular Technique in Salmonella Epidemiological Studies

Salmonella are one of the most widespread micro-organisms found in the global food chain; they are frequently isolated from raw meats, poultry, and milk. They are responsible for a number of clinical syndromes, including gastroenteritis. Pulsed-field gel electrophoresis (PFGE) has been recognized as a powerful tool for molecular typing, and has been the method of choice applied in numerous epidemiological studies of Salmonella . The methods described herein outline (1) Salmonella culture preparation, (2) preparation of agarose-embedded bacterial DNA, (3) restriction endonuclease digestion of DNA-embedded agarose plugs, (4) gel electrophoresis of PFGE plugs, (5) determination of the size of restriction fragments in the PFGE pattern, and (6) chromosomal DNA restriction pattern analysis.