 In the current project, we aim to ideally match host and donor for FMT success in recurrent or refractory CDI. We will establish a clinical standard operating protocol for FMT, we will evaluate its safety and efficacy, and the patient acceptance and quality of life before and after FMT. We will analyse persistence of the donor microbiota within the recipient, define predictive clinical recipient and donor factors for FMT success and correlate them with microbial host and donor metagenomics. 