Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/1996
Publication Date: N/A
Interpretive Summary: Pigs have always been considered the only natural host for disease caused by the bacterial spirochete Serpulina hyodysenteriae. The disease, swine dysentery, is a severe diarrheal disease which results in bloody diarrhea and dehydration in the pig. Recently, two spirochetes similar to S. hyodysenteriae were isolated from rheas, flightless birds related to emus and ostriches. One isolate was from a rhea in Ohio, while the other was from an Iowa rhea farm. These rheas exhibited clinical signs, including diarrhea and intestinal lesions, which were similar to those found in pigs with swine dysentery. We compared these rhea spirochetes with S. hyodysenteriae strains previously isolated from dysenteric pigs to see if they were similar. Our tests included beta-hemolysis on blood agar plates, indole production, immunoblot analysis, RFLP analysis, and 16S rRNA sequencing and phylogenetic analysis. These tests indicated that the rhea spirochetes were the same as the S. hyodysenteriae isolates from pigs. This is the first time that S. hyodysenteriae has been found to cause a naturally occurring disease in any animal except the pig. Comparison of rhea and pig isolates will provide important information on virulence factors involved in pathogenicity in different animal hosts. Understanding these differences will lay the ground work for development of vaccine strategies against disease caused by S. hyodysenteriae.
Technical Abstract: Spirochetes have been observed in the intestinal tracts of different animals including pigs, dogs, chickens, and humans. The porcine intestinal spirochete Serpulina hyodysenteriae causes a severe diarrheal disease called swine dysentery. Recently, intestinal spirochetes were isolated from rheas in Iowa and Ohio with a necrotizing typhlocolitis. These intestinal spirochetes, strains R1 and NIV-1, were characterized and compared with other intestinal spirochetes, including strains of S. hyodysenteriae. Both rhea spirochetes were indole positive, strongly beta-hemolytic, grew under a 1% O2:99% N2 atmosphere, and were morphologically similar to spirochetes in the genus Serpulina. Analysis of rRNA gene restriction patterns (ribotypes), and immunoblots of whole cell proteins, indicated both spirochetes were similar to Serpulina hyodysenteriae strains from swine. Comparisons of nearly complete sequences (more than 1458 bases) of the 16S rRNA gene of the two rhea spirochetes with S. hyodysenteriae strains confirmed that rhea spirochetes R1 and NIV-1 were strains of S. hyodysenteriae. These results indicate that S. hyodysenteriae may have a broader host range than previously recognized.