Dientamoeba fragilis carriage
Bowen, 2016Brands, 2019Byrne, 2015de Boer, 2020Gray, 2013Roser, 2013Stark, 2016Wong, 2018
Historically, Dientamoeba fragilis was detected only by faecal microscopy. With transition to multiplex polymerase chain reaction (PCR) faecal testing, which is more sensitive, it has become evident that carriage of D. fragilis is much more common than previously thoughtMicrobiology Advisory Committee The Royal College of Pathologists of Australasia (RCPA), 2023. However, the pathogenicity of this organism has not been established1.
Identification of D. fragilis in a faecal sample should be interpreted with care – D. fragilis is commonly detected in asymptomatic individuals, and when D. fragilis is identified in a symptomatic patient, symptoms are more likely to have an alternative cause. If the patient has significant abdominal symptoms (eg abdominal pain, diarrhoea), follow up a positive multiplex PCR test with faecal microscopy.
In patients with persistent symptoms and D. fragilis carriage, it is important to investigate for other causes, including irritable bowel syndrome, inflammatory bowel disease, malabsorption syndromes, colon cancer, Clostridioides difficile (formerly known as Clostridium difficile) infection, enteric bacterial infection, HIV-related opportunistic infections, Tropheryma whipplei infection (Whipple disease). Consider referral to a gastroenterologist.
The use of antimicrobial therapy for D. fragilis is controversial. A randomised controlled trial of metronidazole for treatment of D. fragilis in children showed no benefitRoser, 2014. However, treatment may be considered in symptomatic patients in whom D. fragilis has been identified on faecal microscopy or who have eosinophilia, and where other causes have been excluded – seek advice from an infectious diseases physician.
Repeat courses of antibiotics and retesting are not indicated.