Fresh vs. Frozen Stool for FMT, Does it Matter?

Fecal microbiota transplantation (FMT) is the infusion of specially prepared stool material from a healthy donor(s) into the gut (intestinal tract) of a recipient to restore a healthy and stable microbial community and confer health benefits and/or treat a specific disease or symptom(s) ^1–4 (See our blog post to learn more about FMT).

FMT administration can be categorized into either upper or lower GI routes and include nasogastric and nasoduodenal tube, colonoscopy, retention enemas, and oral capsules ^5–10. The preferred route of administration for FMT remains a topic of discussion, and the most optimal mode of administration remains unclear ^7,11 (See our blog post to learn more about the different FMT modes of administration).

Several stool preparations can be utilized for FMT, including fresh, frozen, and lyophilized ¹². One recurrent question in the literature is whether fresh fecal preparations are superior to frozen for FMT. Clinical research has demonstrated that frozen fecal preparations provide similar clinical efficacy in treating recurrent Clostridium difficile infections (rCDI) as fresh fecal preparations in FMT ^{10,11,13–21}. Specifically, Ramai et al. directly compared overall cure rates in rCDI patients and reported a 94.9% cure rate for patients treated with fresh FMT vs. 94.5% in patients treated with frozen FMT ⁸. Based on the clinical literature, it can be concluded that the choice of fresh or frozen fecal preparations for FMT does not affect treatment outcomes ^13,15–17.

Benefits of frozen FMT

As clinical literature reports no differences in the efficacy between fresh and frozen fecal preparations for FMT, it has become possible to store fecal preparations over more extended time periods ^10,17,20,21. The use of frozen fecal preparations offers several advantages over fresh, including:

1. Better donor screening: Frozen preparations may help decrease the potential transmission of pathogens by providing time for the complete extensive donor screening, including blood and stool testing, in advance of FMT ^13,22. In addition, the storage of frozen fecal material allows for retesting of donors and quarantining of samples for possible incubating viral infections ²².
2. Increased accessibility of FMT: Frozen preparations are the most practical approach to improving FMT accessibility by allowing immediate availability of fecal preparations for FMT as testing and screening can be done in advance ^10,13,17. Also, fecal preparations can be prepared at specialist sites and shipped to medical facilities that do not have on-site laboratory facilities, allowing for greater access to FMT for a broader patient population ^13,17.
3. Long-term storage: The ability to store fecal preparations allows for the establishment of stool banks, which increases the accessibility of FMT ^1,18,21,23. In addition, long-term storage of fecal materials from screened donors can reduce the frequency of donor screenings and testing, reducing the overall cost associated with FMT ¹⁰.

At Novel Biome, we believe in the importance of the gut microbiome for overall health and the possibilities of fecal microbiota transplantation (FMT) to restore gut health and treat disease. Novel Biome focuses on FMT product manufacturing and supplying high-quality products, relying on our world-class donors to allow us to make a significant difference in the lives of many individuals, take our eligibility quiz to see if you can be a stool donor.

References: 1. Choi, H. H. & Cho, Y.-S. 2016, 2. Gupta, S. et al. 2021, 3. Ser, H.-L. et al. 2021, 4. Xu, M.-Q. 2015, 5. Cold, F. et al. 2021, 6. Hirsch, B. E. et al. 2015, 7. Ooijevaar, R. E. et al. 2019, 8. Ramai, D. et al. 2021, 9. Smits, L. P. et al. 2013, 10. Tang, G. et al. 2017, 11. Ramai, D. et al. 2019, 12. Gerardin, Y., et al. 2021, 13. Fadda, H. M. 2020, 14. Hamilton, M. J. et al. 2012, 15. Ianiro, G. et al. 2018, 16. Kao, D. et al. 2017, 17. Lee, C. H. et al. 2016, 18. Satokari, R. et al. 2015, 19. Youngster, I. et al. 2014, 20. Quraishi, M. N. et al. 2017, 21. Reigadas, E. et al. 2020, 22. Youngster, I. et al. 2014, 23. Terveer, E. M. et al. 2017.