Clinical Infection in Practice (Nov 2023)
Refractory inflammatory bowel disease – Entamoeba histolytica, the forgotten suspect
Abstract
Background: Amoebiasis is a term used to describe infection caused by the protozoan Entamoeba histolytica. Transmission is linked to exposure to cysts and trophozoites excreted in the stool. Many infections are asymptomatic, but invasive intestinal disease can occur, typically causing amoebic colitis or an amoebic liver abscess (ALA). Methods: We describe two recent cases of invasive amoebiasis, misdiagnosed as Crohn’s Disease (CD). We then retrospectively reviewed 35 serological positive cases that presented to Barts Health NHS Trust over a 5-year period (2017–2022). Results: Of the 35 cases, 22 (63%) were false positives with immunofluorescent antibody titres detected at low level (1/80–1/160). Of the 13 confirmed cases, four patients presented with amoebic colitis, six with an ALA and three has both. Within the cohort, eight patients had travelled abroad and three patients were men who have sex with men (MSM), two without a travel history. No cysts or trophozoites were seen in the stool, but all cases were diagnosed using histopathology, serology, or PCR testing. For cases misdiagnosed as Crohn’s disease (CD), there was no radiological evidence of small bowel disease and histologically, no granulomata seen. There were treatment variations for both the duration and dose of metronidazole and paromomycin but all patients recovered despite immunosuppression in those misdiagnosed as CD. Conclusion: A history of ‘dysenteric illness’ in a MSM in the absence of a travel history is enough to instigate investigations for amoebiasis. Amoebic colitis can be misdiagnosed as CD and in patients not responding to immunosuppression, the diagnosis should be reconsidered.
