Human intestinal spirochetosis: clinicopathological features in patients from a Chilean Academic Health Network

To describe clinical features, endoscopic and histological findings, and follow up in patients with Human intestinal spirochetosis (HIS) from a Chilean academic health center.

A retrospective review was conducted on HIS cases diagnosed in an academic health network in Santiago de Chile between 2018 and 2022. Clinical, endoscopic, histopathological, therapeutic, and follow-up information was collected.

Sixteen colonic samples were identified (0.05% of all colonoscopies'biopsies). The median age was 40 years, 75% were male, and 33% had an antecedent of HIV infection. All patients reported symptoms: diarrhea (67%), abdominal pain (40%), and gastrointestinal bleeding (27%). The majority (69%) had a normal-appearing mucosa upon endoscopy, and the finding of spirochetes occurred predominantly in step biopsies (75%). Histopathological analysis revealed normal mucosal architecture in 88% of cases. Post-colonoscopy follow-up was achieved for 10 patients, 4 of whom received antibiotics with subsequent symptom resolution in the three with post-treatment follow-up. All followed-up patients who did not receive antibiotics reported symptom resolution.

HIS is infrequent and predominantly colonic. Most cases are men, have a history of a sexually transmitted infection, present with gastrointestinal symptoms, and often have a normal colonoscopy. Most samples do not exhibit significant histopathological changes beyond superficial bacterial colonization.