Influence of probiotic and prebiotic supplementation on intestinal microbiota and resistance to Edwardsiella ictaluri infection in channel catfish (Ictalurus punctatus) following florfenicol administration

Authors: Older, Caitlin; GRIFFIN, MATT - Mississippi State University; Richardson, Brad; Waldbieser, Geoffrey - Geoff; REIFERS, JONATHAN - Mississippi State University; GOODMAN, PENELOPE - Mississippi State University; WARE, CYNTHIA - Mississippi State University; GATLIN III, DELBERT - Texas A&M University; WISE, DAVID - Mississippi State University; YAMAMOTO, FERNANDO - Mississippi State University

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2023
Publication Date: 12/28/2023
Citation: Older, C.E., Griffin, M.J., Richardson, B.M., Waldbieser, G.C., Reifers, J.G., Goodman, P.M., Ware, C., Gatlin Iii, D.M., Wise, D.J., Yamamoto, F.Y. 2023. Influence of probiotic and prebiotic supplementation on intestinal microbiota and resistance to Edwardsiella ictaluri infection in channel catfish (Ictalurus punctatus) following florfenicol administration. Journal of Fish Diseases. 47(4):e13910. https://doi.org/10.1111/jfd.13910.
DOI: https://doi.org/10.1111/jfd.13910

Interpretive Summary: Enteric septicemia of catfish (ESC), a bacterial disease caused by Edwardsiella (E.) ictaluri, is a significant threat to catfish aquaculture in the southeastern United States. Antibiotic intervention can reduce mortality, however antibiotic use results in disruption of the bacterial community in the gut, known as the gut microbiota, which may increase the risk of otherwise healthy fish to contracting enteric infections. Scientists at the USDA, ARS, Warmwater Aquaculture Research Unit in Stoneville, MS, along with scientists at Mississippi State University evaluated how the microbiota was affected by a 10-day course of antibiotic administration, and how a prebiotic and probiotic could ameliorate any antibiotic-induced gut microbiota dysbiosis. The gut microbiota was characterized by Illumina sequencing. In addition to evaluating changes in the microbiota, the influence of antibiotic usage and a prebiotic or probiotic containing diet on survivability of channel catfish was evaluated by challenging the remaining fish with E. ictaluri. Florfenicol administration resulted in a disruption of the gut microbiota, which appeared to begin to return to normal within 4 days after cessation of florfenicol administration. Finally, fish fed the probiotic diet had higher survival in response to E. ictaluri challenge than the prebiotic and control groups. "Further research conducted in ponds, where catfish are typically farmed, are warranted to understand if the probiotic could be useful for the U.S. catfish industry."

Technical Abstract: Enteric septicemia of catfish (ESC), caused by the gram-negative enteric bacterium Edwardsiella ictaluri, is a significant threat to catfish aquaculture in the southeastern United States. Antibiotic intervention can reduce mortality, however antibiotic use results in an imbalance, or dysbiosis, of the gut microbiota, which may increase susceptibility of otherwise healthy fish to enteric infections. Herein, recovery of the intestinal microbiota and survivability of channel catfish in response to ESC challenge was evaluated following a 10-day course of florfenicol and subsequent probiotic or prebiotic supplementation. Following completion of florfenicol therapy, fish were transitioned to a basal diet or diets supplemented with a probiotic or prebiotic for the remainder of the study. Digesta was collected on days 0, 4, 8, and 12, beginning on the last day of antibiotic treatment, and gut microbiota characterized by Illumina sequencing of the 16S rRNA gene (V4 region). Remaining fish were challenged with E. ictaluri and monitored for 32 days post-challenge. Florfenicol administration resulted in dysbiosis characterized by inflated microbial diversity, which began to recover in terms of diversity and composition 4 days after cessation of florfenicol administration. Fish fed the probiotic diet had higher survival in response to ESC challenge than the prebiotic (p=0.019) and control (p=0.027) groups.