Faecal microbiota transplant for recurrent Clostridium difficile infection using long‐term frozen stool is effective: clinical efficacy and bacterial viability data

Summary Background Faecal microbial transplant (FMT) for recurrent Clostridium difficile infection (rCDI) is greatly facilitated by frozen stool banks. However, the effect of frozen storage of stool for greater than 2 months on the viability of stool bacteria is unknown and the efficacy of FMT is not clear. Aim To evaluate the viability of bacteria in stool frozen for up to 6 months, and the clinical efficacy of FMT with stool frozen for 2–10 months, for the treatment of rCDI. Methods Viability of six representative groups of faecal bacteria after 2 and 6 months of storage at −80 °C, in normal saline (NS) or 10% glycerol were assessed by culture on plate media. The clinical outcomes of 16 consecutive patients with rCDI treated with aliquots of stool frozen in 10% glycerol and stored for 2–10 months were also examined. Results Viability at both 2 and 6 months was similar to baseline, in specimens stored in 10% glycerol and at 2 months in stool stored in NS, but was reduced by >1 log at 6 months for Aerobes (P