Analysis of Serpulina hyodysenteriae strain variation and its molecular epidemiology using pulsed-field gel electrophoresis

Pulsed-held gel electrophoresis (PFGE) was applied as a molecular typing to ol for the spirochaete Serpulina hyodysenteriae, the agent of swine dysente ry. Analysis of a collection of 40 mainly Australian isolates, previously c haracterized by other methods, divided these into 23 PFGE types. This confi rmed that there are many strains of the spirochaete in Australia. PFGE was more discriminatory for strain typing than both multilocus enzyme electroph oresis and serotyping. It had similar discriminatory power to restriction e ndonuclease analysis, but the results of PFGE were easier to interpret. Whe n applied to 29 isolates collected from 4 farms over periods of up to 8 yea rs, 2 PFGE patterns were found on 3 farms, and a single pattern on the othe r. In each case a new strain had apparently emerged as a variant of an orig inal parent strain. PFGE was found to be a powerful technique for investiga ting the molecular epidemiology of swine dysentery outbreaks.