Background: Fecal microbial transplantation (FMT) is increasingly utilized in canine medicine. Convenient storage facilitates the use of FMT in practice, however the long-term effect of freezing and lyophilization on microbial viability is unknown.
Objectives: Our study aims to quantitate the colony forming units (CFUs) of microbes within canine FMT products using culture-based techniques in aerobic and anaerobic environments.
Animals: Three screened healthy canine fecal donors each provided three separate fresh fecal samples for processing.
Methods: Fecal processing techniques include unprocessed and three double-centrifuged fecal slurries with the following additives: 0.9% saline, 10% glycerol, and 25% maltodextrin and trehalose (M:D). FMT aliquots were stored at -20C, -80C, and lyophilized for storage at room temperature. Timepoints for CFU/gram quantitation include baseline, 1-, 3-, 6-, and 12-months.
Results: At the 12-month timepoint, lyophilized products preserved with M:D yielded significantly greater total CFUs compared with other lyophilized FMT products (p<0.01). For FMT products frozen at -20C, FMT preserved with glycerol and M:D yielded significantly more CFUs than other products (p<0.01), with no significant difference between glycerol and M:D (p=0.06). All FMT products, except 10% glycerol frozen at -80C, exhibited a significant decrease in total CFUs over the 12-month period (p<0.01). For all products, storage at -80C yielded significantly more total CFUs than storage at -20C (p<0.01).
Conclusions and clinical importance: This study provides clinicians with evidence for producing and storing canine FMT in their own practice. Further research is needed to determine whether increased CFUs translates to microbe engraftment and thus additional clinical benefit.
