Identification of Serpulina species associated with porcine colitis by biochemical analysis and PCR.

A PCR system for the detection and identification of group IV spirochetes (Serpulina pilosicoli) was designed to complement biochemical tests, e.g., the hippurate hydrolysis and beta-glucosidase tests, and to verify the accuracy of a previously proposed biochemical classification system. The PCR assay was based on amplification of a segment of the 16S rRNA gene. Both primers were constructed to selectively amplify the 16S rRNA gene of Serpulina pilosicoli. All analyzed Serpulina strains exhibiting the capacity to hydrolyze hippurate and lacking beta-glucosidase activity, including the type strain for spirochetal diarrhea, P43, were amplified with the PCR system. All other tested strains, including type and field strains of different phenotypes of Serpulina species, as well as Salmonella species, Campylobacter species, and Escherichia coli strains, were negative in the assay. Among the tested strains were 18 Scottish field isolates originating from the mucosae of pigs with colitis. A simple classification scheme, suitable for routine classification of porcine intestinal spirochetes, is also presented. The scheme is based on hemolysis, indole production, and the hippurate hydrolysis test.