In vitro evaluation of the effect of storage at -20°C and proximal gastrointestinal conditions on viability of equine fecal microbiota transplant

Abstract Fecal microbiota transplant (FMT), a technique used to restore normal intestinal microbial communities, has been successful in treating humans with Clostridioides difficile colitis. Subsequently, FMT is being utilized in veterinary patients with suspected intestinal dysbiosis. Unfortunately, little data is available regarding best practices for FMT in horses. The objective of this study was to evaluate the effects of storing manure prepared for equine FMT (MP-FMT) at -20°C for up to four weeks and passage through a simulated proximal gastrointestinal (GI) tract on the viability of MP-FMT. Results from this study indicate that storage at -20°C for greater than one week and exposure to conditions consistent with the proximal GI tract significantly decreased viability of the microbial population, with Gram-negative enteric bacteria most significantly impacted. This preliminary evaluation indicates that further work is necessary to determine best practices to preserve the viability MP-FMT in horses.