Simple faecal preparation and efficacy of frozen inoculum in faecal microbiota transplantation for recurrent <i><scp>C</scp>lostridium difficile</i> infection – an observational cohort study

Faecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridium difficile infection (rCDI). The finding of suitable donor, donor screening and preparation of faecal transplants are challenging in clinical work.To develop a practical protocol for preparing frozen transplants and to compare the efficacy of previously frozen and fresh faeces in treating rCDI.Two healthy volunteers acted as universal donors for the frozen faecal preparations, which were prepared by suspending faeces into physiological saline, adding glycerol to a final concentration of 10% and storing at -80 °C. We compared the outcomes of patients with rCDI who had undergone FMT at colonoscopy and received infusion of previously prepared, freeze-stored faeces (n = 23) or fresh faeces from individual (n = 15) or universal donors (n = 11) (total n = 49). Clinical failure was defined as persistent or recurrent symptoms with a positive C. difficile toxin stool test, and a need for new therapy.At 12 weeks post-FMT, symptoms were resolved in 22 of 23 patients receiving previously frozen faeces, and in all 11 or 14 of 15 patients receiving fresh faeces from the universal or individual donors respectively (totally 25 of 26; P = ns, success rate 96%). Mild transient fever appeared for two patients receiving frozen faeces, but no other significant side effects were observed. 42 patients were followed up for a year post-FMT and the success rate was 88% in both fresh and frozen faeces groups.Preparation of frozen transplants simplifies the practical aspects of faecal microbiota transplantation without loss of efficacy or safety.