An outbreak and source investigation of enterococcal spondylitis in broilers caused by Enterococcus cecorum.

Enterococcus cecorum was isolated from spondylitis lesions in broilers from two flocks in North Carolina that were experiencing increased mortality. Affected birds showed paresis and paralysis, clinical signs characteristic of enterococcal spondylitis (ES). Affected birds rested on their hocks and caudal abdomens with legs extended forward and were unable to stand or walk. Necropsy examination of affected birds revealed firm to hard inflammatory masses involving the vertebral bodies at the level of the free thoracic vertebra that bulged dorsally and compressed the spinal cord. When opened, lesions contained pale, tan to yellow caseonecrotic material. Microscopically, necrosis and fibrinoheterophilic spondylitis with intralesional gram-positive bacteria were seen. Heavy growth of E. cecorum recovered from vertebral lesions confirmed the diagnosis of ES. To investigate possible sources of the organism for one of the flocks bacterial cultures were made from the environment, water lines, mice trapped on the farm, cecal/cloacal swabs from one of the parent broiler breeder flocks, egg residue, hatching eggs, and the hatchery environment. Except for cecal/cloacal swabs from the breeders, E. cecorum was not isolated from any of these samples. When compared phenotypically and genotypically, cecal/cloacal isolates of E. cecorum from the breeders differed from isolates from spondylitis lesions in the broilers. The source of E. cecorum for the broiler flocks was not determined, but vertical transmission appears unlikely.