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, χ(2) 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.