DEVELOPMENT AND EVALUATION OF POLYMERASE-CHAIN-REACTION TESTS AS AN AID TO DIAGNOSIS OF SWINE-DYSENTERY AND INTESTINAL SPIROCHETOSIS

Polymerase chain reaction (PCR) tests were established for detection o f Serpulina hyodysenteriae, the agent of swine dysentery, and S. pilos icoli, the agent of intestinal spirochaetosis. Both reactions were spe cific when tested with DNA from 107 strains of various intestinal spir ochaetes. For diagnostic use, faeces were plated to selective medium, and diatomaceous earth extraction used to obtain DNA prior to PCR. Thi s procedure detected 10(3)-10(4) cells of either organism seeded into 0.2 g of faeces. When applied to 63 samples from pigs of eight piggeri es naturally infected with either S. hyodysenteriae or S. pilosicoli, both PCRs were specific, more rapid, and detected more positive sample s than did routine faecal culture and isolation.