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

Aliment Pharmacol Ther. 2015 Oct;42(8):1011-8. doi: 10.1111/apt.13366. Epub 2015 Aug 11.


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 < 0.01), total Coliforms (P < 0.01) and Lactobacilli (P < 0.01) in NS. Using stool frozen for 2-10 months in 10% glycerol, the cure rate for rCDI was 88% with one FMT and 100% after repeat FMT in those who relapsed.

Conclusion: Stool for faecal microbial transplant to treat rCDI can be safely stored frozen in 10% glycerol for at least 6 months without loss of clinical efficacy or viability in the six bacterial groups tested.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Clostridioides difficile* / pathogenicity
  • Clostridioides difficile* / physiology
  • Clostridium Infections / microbiology
  • Clostridium Infections / therapy*
  • Fecal Microbiota Transplantation*
  • Feces / microbiology*
  • Female
  • Freezing
  • Humans
  • Male
  • Microbial Viability
  • Middle Aged
  • Recurrence
  • Retrospective Studies
  • Secondary Prevention / methods*
  • Specimen Handling / methods*
  • Treatment Outcome