Colonizing the Unlikely: Brachyspira in an Immunocompetent Patient.

Chronic diarrhea is a common condition that medical professionals often encounter. We present an unusual case of chronic diarrhea in a relatively young, immunocompetent man that was attributed to Brachyspira . The patient's clinical presentation was not specific, and he underwent workup for common infectious, inflammatory, and autoimmune causes, all unrevealing. During colonoscopy, no abnormalities were detected; however, histopathology revealed the presence of Brachyspira . Following a course of metronidazole, the patient showed marked improvement in his diarrhea. It is worth noting that the patient's social history did not align with the established risk factors mentioned in the existing literature.