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Journal of Clinical Microbiology, February 2008, p. 593-600, Vol. 46, No. 2
0095-1137/08/$08.00+0 doi:10.1128/JCM.01829-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Animal Health Service (GD), P.O. Box 9, 7400 AA Deventer, The Netherlands,1 School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia,2 Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands3
Received 14 September 2007/ Returned for modification 20 November 2007/ Accepted 28 November 2007
Cecal samples from laying chickens from 25 farms with a history of decreased egg production, diarrhea, and/or increased feed conversion ratios were examined for anaerobic intestinal spirochetes of the genus Brachyspira. Seventy-three samples positive in an immunofluorescence assay for Brachyspira species were further examined using selective anaerobic culture, followed by phenotypic analysis, species-specific PCRs (for Brachyspira hyodysenteriae, B. intermedia, and B. pilosicoli), and a Brachyspira genus-specific PCR with sequencing of the partial 16S rRNA gene products. Brachyspira cultures were obtained from all samples. Less than half of the isolates could be identified to the species level on the basis of their biochemical phenotypes, while all but four isolates (5.2%) were speciated by using PCR and sequencing of DNA extracted from the bacteria. Different Brachyspira spp. were found within a single flock and also in cultures from single chickens, emphasizing the need to obtain multiple samples when investigating outbreaks of avian intestinal spirochetosis. The most commonly detected spirochetes were the pathogenic species B. intermedia and B. pilosicoli. The presumed nonpathogenic species B. innocens, B. murdochii, and the proposed "B. pulli" also were identified. Pathogenic B. alvinipulli was present in two flocks, and this is the first confirmed report of B. alvinipulli in chickens outside the United States. Brachyspira hyodysenteriae, the agent of swine dysentery, also was identified in samples from three flocks. This is the first confirmed report of natural infection of chickens with B. hyodysenteriae. Experimental infection studies are required to assess the pathogenic potential of these B. hyodysenteriae isolates.
Published ahead of print on 12 December 2007.
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