Retrospective Cohort Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 14, 2020; 26(26): 3792-3799
Published online Jul 14, 2020. doi: 10.3748/wjg.v26.i26.3792
Two-day enema antibiotic therapy for parasite eradication and resolution of symptoms
Niloufar Roshan, Annabel Clancy, Anoja W Gunaratne, Antoinette LeBusque, Denise Pilarinos, Thomas J Borody
Niloufar Roshan, Annabel Clancy, Anoja W Gunaratne, Antoinette LeBusque, Denise Pilarinos, Thomas J Borody, Centre for Digestive Diseases, New South Wales 2046, Australia
Author contributions: Roshan N was involved in data collection, analysis and writing the original draft; Clancy A was involved in supervision, writing, review and editing; Gunaratne AW contributed to the data collection and writing review; LeBusque A performed the data collection and writing review; Pilarinos D was involved in data collection and writing review; Borody TJ contributed to the supervision, writing review and editing; All authors have read and approve the final manuscript.
Institutional review board statement: This study was approved by the institutional ethics committee (CDD19/C02).
Informed consent statement: A waiver of consent was granted for this study. Patients were not required to give informed consent for this study because the analysis used de-identified data that was obtained after each patient agreed to treatment.
Conflict-of-interest statement: : Professor Thomas J Borody has a pecuniary interest in the Centre for Digestive Diseases and has filed patents for antibiotic therapies for parasitic infections. Dr Niloufar Roshan, Dr Annabel Clancy, Dr Anoja Gunaratne, Ms Antoinette LeBusque and Ms Denise Pilarinos have no disclosures.
Data sharing statement: All data requests should be submitted to the corresponding author for consideration.
STROBE statement: The authors have read the STROBE statement-checklist of items, the manuscript was prepared according to the STROBE statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Niloufar Roshan, PhD, Research Fellow, Research, Centre for Digestive Diseases, Level 1, 229 Great North Road, New South Wales 2046, Australia.
Received: November 19, 2020
Peer-review started: November 19, 2020
First decision: April 2, 2020
Revised: May 9, 2020
Accepted: June 20, 2020
Article in press: June 20, 2020
Published online: July 14, 2020

Blastocystis hominis (B. hominis) and Dientamoeba fragilis (D. fragilis) are two protozoan parasites of human bowel that are found throughout the world. There is still debate about the pathogenicity of these protozoans, despite them being commonly associated with gastrointestinal symptoms and can cause health issue in both children and adults. These parasites are usually transmitted through faecal-oral contact particularly under poor hygiene conditions or food/water contamination. Once a person is infected, the parasites live in the large intestine and are passed in the faeces.


To investigate the effect of triple antibiotic therapy using enema infusion in the treatment of B. hominis and D. fragilis infections.


This retrospective longitudinal study was conducted in a single medical centre, which included fifty-four patients (≥ 18 years) who were positive for D. fragilis, B. hominis or both between 2017 and 2018. The treatment consisted of triple antibiotics that were infused over two consecutive days through rectal enema. Faecal samples were collected from participants pre- and post-treatment and were tested for parasites using microscopy and polymerase chain reaction. Patients’ symptoms were recorded prior and after the treatment as well as patient demographic data.


Patients (n = 54), were either positive for B. hominis (37%), D. fragilis (35%) or both (28%). All patients completed the two-day treatment and no serious adverse effect was reported. The most common side effect experienced by the patients during the treatment was urine discolouration which was cleared by six weeks of follow-up. Common symptoms reported prior to treatment were diarrhoea, abdominal pain, constipation and fatigue. Other symptoms included abdominal discomfort, dizziness and blood in the stool. Eighty-nine percent of patients completed a final stool test post-treatment. At six weeks post-treatment, 79% of patients cleared the parasites from their faeces. Symptoms such as abdominal discomfort, dizziness and blood in the stool decreased significantly at both seven days and six weeks post-treatment (P < 0.040). The enema retention time, bowel preparation, previous antibiotic treatment or previous gastrointestinal problems had no significant effect on parasite eradication.


Overall, eradication of parasites and improvement of clinical outcomes were observed in treated patients, showing the efficacy of this combination to eradicate the parasites and provide positive clinical outcome.

Keywords: Blastocystis hominis, Dientamoeba fragilis, Parasitic infection, Antibiotics, Triple therapy, Rectal enema route

Core tip: Intestinal parasitic infections caused by Blastocystis hominis (B. hominis) and Dientamoeba fragilis (D. fragilis) have the ability to cause illness. This study investigated the effect of a triple antibiotic therapy using 2-d enema infusion for treatment of patients who were positive to B. hominis, D. fragilis or both. A significant reduction in major symptoms as well as parasite eradication were observed post-treatment. Larger clinical trials should further investigate improvements of such therapy using larger volume enemas and alternative delivery routes.