Treatment of Dientamoeba fragilis: A retrospective Finnish analysis of faecal clearance and clinical cure comparing four antiprotozoal drugs

Jukka-Pekka Pietilä; Tuuve A Häkkinen; Laura Pakarinen; Jukka Ollgren; Anu Kantele

doi:10.1016/j.nmni.2023.101179

Treatment of Dientamoeba fragilis: A retrospective Finnish analysis of faecal clearance and clinical cure comparing four antiprotozoal drugs

New Microbes New Infect. 2023 Sep 23:54:101179. doi: 10.1016/j.nmni.2023.101179. eCollection 2023 Sep.

Authors

Jukka-Pekka Pietilä^{1

2}, Tuuve A Häkkinen^{1

2}, Laura Pakarinen^{3

4}, Jukka Ollgren⁵, Anu Kantele^{1

2

3

6}

Affiliations

¹ Meilahti Vaccine Research Center MeVac, Department of Infectious Diseases, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
² Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
³ Department of Infectious Diseases, Inflammation Center, Helsinki University Hospital, Helsinki, Finland.
⁴ Department of Social Services and Health Care, City of Helsinki, Finland.
⁵ Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, Finland.
⁶ Finnish Multidisciplinary Center of Excellence in Antimicrobial Resistance Research, FIMAR, University of Helsinki, Helsinki, Finland.

Abstract

Background: Dientamoeba fragilis (DF), the most common intestinal protozoal pathogen in affluent countries, causes asymptomatic or symptomatic infections with severity ranging from mild to disabling. Currently, many studies of treatment options only have small sample sizes and report results that are partly contradictory.

Methods: Investigating data retrieved from Helsinki University Hospital and Helsinki City patient records, we searched for the most effective antiprotozoal in treating DF infections. To study microbiological clearance of DF, we collected laboratory results of control samples from patients given one of four commonly used antiprotozoals: doxycycline, metronidazole, paromomycin, or secnidazole. For patients symptomatic prior to antiprotozoal treatment, we also retrieved data on clinical outcomes. Furthermore, we explored factors associated with faecal clearance and clinical cure.

Results: A total of 369 patients (median age 38) and 492 treatment episodes were included. Paromomycin (n = 297) proved effective (clearance rate 83%), showing strong association with faecal clearance (aOR 18.08 [7.24-45.16], p < 0.001). For metronidazole the rate was 42% (n = 84), for secnidazole 37% (n = 79), and doxycycline 22% (n = 32). In pairwise comparisons, paromomycin outdid the three other regimens (p < 0.001, χ² test). Faecal clearance was associated with clinical cure (aOR 5.85 [3.02-11.32], p < 0.001).

Conclusions: Faecal clearance, strongly associated with clinical cure, is most effectively achieved with a course of paromomycin, followed by metronidazole, secnidazole and doxycycline. Our findings will be useful in devising treatment guidelines for adults with symptomatic D. fragilis infection.

Keywords: Chronic diarrhoea; Diarrhoea; Dientamoeba fragilis; Doxycycline; Metronidazole; Parasite; Paromomycin; Secnidazole; Stomachache; Stool pathogen.