Intestinal spirochetosis in a guinea pig with colorectal prolapse.

Intestinal spirochetosis in a guinea pig with colorectal prolapse A 6-month-old, male guinea pig, kept as a pet, was preAsented to a veterinary clinic due to a rectal prolapse. The clinical examination revealed tenesmus, pale mucous membranes, tachycardia, a tense abdominal wall, and mild dehydration. The prolapsed intestinal segment was 7 cm long; the distal 2/3 of the exposed mucosa appeared necrotic, and the proximal 1/3 was hemorrhagic. Considering the poor prognosis and the cost of surgery, the owner opted to have the animal euthanized. The owner's daughter, who kept the guinea pig in her room, had developed diarrhea and vomiting 2 d prior to this incident. The guinea pig was submitted to our diagnostic laboratory for necropsy. Gross examination showed that the rectum and the distal part of the colon were prolapsed with marked passive congestion of the intussuscepted segment. In the proximal colon, content was normal. Other organs did not have significant changes. Microscopic examination of the prolapsed intestinal segment revealed marked congestion with hemorrhage and superficial mucosal necrosis and ulceration. Diffusely in the cecum and multifocally in the proximal part of the colon, there was colonization of the superficial epithelium by filamentous bacteria, oriented perpendicularly to the mucosal surface; a Warthin-Starry stain showed the bacteria to have Brachyspira-like morphology. In the proximal colon, protozoa, morphologically compatible with Eimeria caviae, were seen in crypt epithelium. No mucosal changes were associated with either the bacteria or the coccidia. There were no significant changes in the other organs. Bacteriological cultures of the colon and a sample of the feces were negative for Brachyspira, Yersinia, Salmonella, and Listeria. A polymerase chain reaction (PCR) test for Brachyspira pilosicoli (formerly named Serpulina pilosicoli) was done on the same samples; the PCR results were positive for the colonic sample and negative for the fecal sample. The colorectal prolapse was not considered to be associated with either the spirochetosis or the coccidial infection. However, since B. pilosicoli is an agent of uncertain zoonotic potential and the owner's daughter had signs of gastroenteritis, the owner was contacted as soon as the positive PCR test result for B. pilosicoli was received. The clinical signs in the family members had not resolved and all 4 had developed similar signs. The owner went to a medical clinic with this information but was told that viral gastroenteritis had been diagnosed in several patients in recent weeks. It is not known if fecal cultures were done on any member of the family. Intestinal spirochetosis has been reported in humans, nonhuman primates, pigs, dogs, opossums, and guinea pigs (1). Three reports of this condition in guinea pigs were found. One was a single case in which intestinal Tyzzer's disease was diagnosed, and mucosal colonization with spirochetes was of unknown significance (2). Another report described 3 cases; 2 with Tyzzer's disease, with spirochete organisms found mainly in cecocolic crypts, and 1 with necrotizing typhlitis, associated with large numbers of spirochetes in the entire thickness of the cecal wall (3). In the 3rd report, many animals were affected with catarrhal to hemorrhagic typhlocolitis associated with mucosal colonization by Serpulina-like organisms and spirochetosis was considered as the cause of the lesions (4). In these reports, the agents were identified by morphologic criteria as spirochetes or Serpulina-like bacteria, but definitive identification of the agent was not made. To the best of our knowledge, this is the first report to identify B. pilosicoli in guinea pigs by using PCR technology. Brachyspira pilosicoli has been identified in several species, but its zoonotic potential is yet to be determined (5). Fecal cultures on the owner's daughter would have been interesting in this regard.