S5040 The Hidden Spiral: Unmasking Colonic Spirochetosis in a Young Adult

Introduction: Intestinal spirochetosis (IS) is a recognized cause of chronic diarrhea. This condition is characterized by the colonization of the colonic and rectal mucosa by anaerobic spirochetes, primarily from the genus Brachyspira, including Brachyspira aalborgi and Brachyspira pilosicoli. The clinical presentation of intestinal spirochetosis can vary widely, ranging from asymptomatic colonization to chronic mucosal diarrhea, abdominal pain, and rectal bleeding. Diagnosis is typically made through histological examination of colonic and rectal biopsy samples, where spirochetes can be visualized using silver stains like Warthin-Starry. Case Description/Methods: A 26-year-old man with a medical history of hiatal hernia and gastroesophageal reflux disease presented to the gastroenterology clinic with a 2-month history of chronic diarrhea. His symptoms included unintentional weight loss, bloating, and crampy abdominal pain that was not associated with food intake or heartburn. He also reported episodes of nocturnal diarrhea. The physical examination was unremarkable, and initial laboratory tests and stool studies, including cultures and tests for ova, parasites, and Clostridioides difficile toxin, were negative. Colonoscopy showed normal-appearing mucosa; however, due to ongoing symptoms, colonic biopsies were taken. Histological examination demonstrated numerous spirochetes coating the colonic mucosal surface, highlighted by a Warthin-Starry stain, confirming a diagnosis of colonic spirochetosis. Discussion: IS has been documented as a cause of chronic diarrhea in both immunocompetent and immunocompromised individuals. While it is more frequently associated with immunosuppression, case reports and studies confirm its pathogenic role in immunocompetent patients as well. The clinical presentation in immunocompetent individuals may include chronic watery diarrhea, abdominal pain, and occasionally rectal bleeding. Treatment with metronidazole is effective in most cases, leading to symptom resolution and histological clearance of the infection. In some cases, spontaneous resolutions have been observed, but persistent symptoms warrant targeted therapy. Although colonic spirochetosis is rare and often underdiagnosed, its potential to cause chronic diarrhea in immunocompetent patients underscores the importance of considering it in the differential diagnosis of chronic gastrointestinal symptoms, particularly when other common causes have been excluded.