Development and evaluation of polymerase chain reaction tests as an aid to diagnosis of swine dysentery and intestinal spirochaetosis

Polymerase chain reaction (PCR) tests were established for detection of Serpulina hyodysenteriae, the agent of swine dysentery, and S. pilosicoli, the agent of intestinal spirochaetosis. Both reactions were specific when tested with DNA from 107 strains of various intestinal spirochaetes. For diagnostic use, faeces were plated to selective medium, and diatomaceous earth extraction used to obtain DNA prior to PCR. This procedure detected 10³–10⁴ cells of either organism seeded into 0·2 g of faeces. When applied to 63 samples from pigs of eight piggeries naturally infected with either S. hyodysenteriae or S. pilosicoli, both PCRs were specific, more rapid, and detected more positive samples than did routine faecal culture and isolation.