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Updated: Apr 5, 2026
Fecal Microbiota Transplantation via Colonoscopy for Recurrent C. difficile Infection
Published on: December 8, 2014
Faecal microbiota transplant for recurrent Clostridium difficile infection using long-term frozen stool is effective:
S P Costello1,2,3, M A Conlon4, M S Vuaran4
1IBD Service, Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA, Australia.
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.
Insights
Frozen stool storage for fecal microbial transplant (FMT) is effective for treating recurrent Clostridium difficile infection (rCDI). Stool remains viable and clinically effective for FMT for up to 6 months when frozen in 10% glycerol.
Area of Science:
- Microbiology
- Gastroenterology
- Infectious Diseases
Background:
- Frozen stool banks facilitate fecal microbial transplant (FMT) for recurrent Clostridium difficile infection (rCDI).
- The impact of prolonged frozen storage (>2 months) on bacterial viability and FMT efficacy remains unclear.
Purpose of the Study:
- To assess bacterial viability in stool frozen for up to 6 months.
- To evaluate the clinical efficacy of FMT using stool frozen for 2-10 months for rCDI treatment.
Main Methods:
- Bacterial viability was assessed by culture after 2 and 6 months of storage at -80°C in normal saline or 10% glycerol.
- Clinical outcomes of 16 rCDI patients treated with frozen stool (10% glycerol, 2-10 months storage) were examined.
Main Results:
- Stool stored in 10% glycerol showed sustained bacterial viability at 6 months.
- Normal saline storage led to significant viability loss for aerobes, coliforms, and lactobacilli by 6 months.
- FMT with stool frozen in 10% glycerol achieved an 88% cure rate after one treatment and 100% after repeat treatment for rCDI.
Conclusions:
- Stool can be safely frozen in 10% glycerol for at least 6 months for FMT.
- Frozen stool maintains bacterial viability and clinical efficacy for treating rCDI.
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