LABORATORY IDENTIFICATION AND ENTEROPATHOGENICITY TESTING OF SERPULINA-PILOSICOLI ASSOCIATED WITH PORCINE COLONIC SPIROCHETOSIS

Pathogenic intestinal spirochetes of swine include Serpulina hyodysent eriae, a strongly beta-hemolytic spirochete that causes swine dysenter y, and S. pilosicoli, a weakly beta-hemolytic intestinal spirochete (W BHIS) that causes porcine colonic spirochetosis. Because of the existe nce of nonpathogenic WBHIS in the normal swine colon, it is important to develop laboratory procedures for accurate identification of S. pil osicoli. The purpose of the present study was to assess hippurate hydr olysis and polymerase chain reaction (PCR) amplification of specific 1 6S ribosomal RNA (rRNA) sequences for identification of porcine S. pil osicoli. Additionally, the enteropathogenicity of 8 field isolates of porcine S. pilosicoli was determined by challenge exposure of 1-day-ol d chicks and sequential histologic examination of the cecal mucosa. Th e field isolates of porcine S. pilosicoli hydrolyzed hippurate and yie lded S. pilosicoli-specific products by PCR amplification of 16S rRNA sequences. Although all of the field isolates of porcine S. pilosicoli attached to the cecal epithelium of challenge-exposed chicks by day 2 1 postinoculation, some isolates had locally invasive phenotypes. We c oncluded that identification of porcine S. pilosicoli could be made on the basis of results of hippurate hydrolysis and 16S rRNA PCR amplifi cation. Challenge inoculation of 1-day-old chicks followed by histolog ic examination of the cecal mucose demonstrated the enteropathogenicit y of porcine S. pilosicoli.