Isolation and Characterization of Campylobacter hepaticus from Layer Chickens with Spotty Liver Disease in the United States.

Spotty liver disease (SLD) is characterized by multifocal liver lesions, mortality, and drop in egg production. The disease is emerging in Europe and Australia, particularly in free-range and floor-raised layer flocks. Campylobacter hepaticus has been recently identified as the causative agent of SLD. We report the isolation and characterization of C. hepaticus from livers of laying hens affected with SLD in the United States. Two isolates were characterized and found to be highly similar to those described from SLD cases in the United Kingdom and Australia. Initial isolation of C. hepaticus from liver samples required microaerophilic and thermophilic conditions and incubation for a particularly long duration (approximately 7 days). Morphologic and phenotypic properties of the isolates were typical for Campylobacter spp. Phylogenetic analysis based on 16S ribosomal RNA gene sequences and detection of a glycerol kinase gene confirmed the identity of the isolates as C. hepaticus. To the authors' knowledge, this is the first report of C. hepaticus isolation from layer chickens with SLD in the United States. With the increasing changes in the egg industry from conventional cages to cage-free housing systems, the incidence and economic impact of SLD could become significant.