Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 1996
Publication Date: N/A
Interpretive Summary: We identified spirochetes (a type of bacterium) from the intestines of humans, dogs, birds, and swine. Some of the humans and animals were suffering from diarrhea. We found that intestinal spirochetes from diseased humans are close relatives of an intestinal spirochete demonstrated to cause disease in swine ("intestinal spirochetosis"). This suggests the human strains cause intestinal disease in humans. We found that a spirochete isolated from diseased birds is a strain of Serpulina hyodysenteriae, the bacterium that causes swine dysentery. This study is significant to laboratory diagnosticians since it points out that there is a variety of intestinal spirochetes, some of which are pathogens. Specific diagnostic tests for S. hyodysenteriae and other intestinal spirochetes must be developed. This study is significant to animal and human health and provides the first evidence that S. hyodysenteriae can naturally infect animals other than swine. The possibility exists that spirochetes causing diarrhea in animals can be transmitted or have been transmitted to humans and cause diarrhea in humans.
Multilocus enzyme electrophoresis (MEE) analysis and comparisons of nearly complete 16S rRNA gene sequences (1,416 nucleotide positions) were used to evaluate phylogenetic relationships among Serpulina hyodysenteriae strain B78**T, S. innocens strain B256**T, Brachyspira aalborgi strain 513A**T, and eight strains of uncharacterized swine, avian, and human intestinal spirochetes. From MEE analysis, nine strains could be assigned to five groups containing other intestinal spirochetes (genetic distances between groups = 0.6-0.9). Chicken spirochete strain C1 and B. aalborgi 513A**T represented unique electrophoretic types and formed their own MEE groups. Despite MEE differences, the eleven strains had highly similar (96.3-99.9%) 16S rRNA sequences. These findings point out limitations of both MEE analysis and 16S rRNA sequence comparisons when used as solitary techniques for classifying intestinal spirochetes related to Brachyspira/Serpulina species.