Clostridioides difficile infection (CDI) is one of the most common hospital-acquired infectious diseases with a high mortality rate (6-30%). The treatment of CDI, especially the recurrent form of the disease is still considered a challenge. The FILTRATE randomized controlled trial aims to investigate the safety and efficacy of fecal filtrate transplantation in the treatment of recurrent CDI and compare it with conventional fecal microbiota transplantation (FMT).

The treatment of recurrent CDI is still a burden on the healthcare system. FMT is highly effective for the treatment of recurrent CDI, resulting in the resolution of CDI up to 100% of the cases. FMT also has a good short-term safety profile, however long-term events like transfer of multiresistant bacteria and other living microorganism is still a major problem. On the other hand, the fecal filtrate contains only bacterial debris, proteins, and antimicrobial compounds and not intact microorganisms.

The FILTRATE trial is a multicenter, two-arm randomized controlled trial, and aims to compare the safety and efficacy of fecal filtrate transplantation to conventional fecal microbiota transplantation (FMT) in the treatment of recurrent CDI. Adult patients with multiple recurrent (>1) CDIs will be randomized 1:1 to receive either FMT or fecal filtrate transplantation. The transplantation will be carried out using lyophilized capsule on each arm. The primary endpoint of the study will be the clinical resolution of CDI-associated diarrhea 8 weeks after the interventions. Questionnaires will be completed on enrollment and at the time of each follow-up. Adverse events will be recorded and reported to the relevant institutional and national ethics committee. After the intervention, a one-year follow-up is also planned. Blood and stool samples will be collected at baseline and at each follow-up.

Inclusion Criteria:

• age ≥18 years
• multiple recurrent CDI (≥2 previous episodes of CDI)
• at least 3 or more loose or watery stools (Bristol 5-7) per day
• a positive Glutamate Dehydrogenase (GDH)-enzyme and positive CDI toxin A and/or B test
• the patient or the legal guardian sign the written informed consent

Exclusion Criteria:

• pregnancy or breastfeeding
• ongoing antibiotic treatment
• fulminant CDI
• previous FMT
• immunodeficiency
• need of intensive care
• requirement for vasoactive drugs
• other cause of diarrhea
• inflammatory bowel diseases
• irritable bowel syndrome
• life expectancy shorter than 3 months
• unavailable for follow-up visits