Excess Dietary Metal Supplementation Modulates the Gut Microbiome and Host Resilience During Enteric Infection

Objectives: Enterotoxigenic E. coli (ETEC) serves as one of the leading causes of diarrheal disease in children less than 5 years of age. Trace metals have been suggested as an alternative to antibiotics due to their ability to modulate the virulence of bacterial pathogens. This study aims to evaluate the role of dietary trace metals in the onset of ETEC and the development of antimicrobial resistance genes (ARG) in a piglet model. Methods: Fifty weanling pigs were blocked by sex and body weight then randomly assigned to one of five dietary treatments (n=10/treatments) for 24 days. Piglets were fed 1. Low iron diet with iron dextran injection (200 mg) 2. Iron adequate diet (120mg Fe/kg) 3. High iron diet (1,200mg Fe/kg) 4. High copper diet (250mg Cu/kg) 5. High zinc diet (2,500mg Zn/kg). On day 13, all pigs were orally administered an F18 positive ETEC inoculant (10ˆ10 CFU/dose) for 4 consecutive days. Fecal samples were collected on days 1, 6, 12, 15, 18, 21, and 24. Samples were collected and stored at -80˚C. Results: No differences in body weight or feed conversion ratio were observed. On D24, high copper treated pigs had lower hemoglobin and hematocrit values compared to the control group (p< 0.05). 16SrRNA sequencing revealed that treatments did not affect the evenness of species abundances, however, a high zinc diet reduced both species richness and phylogenetic diversity (q< 0.001). Significant differences in beta diversity was observed across treatment groups, as indicated by Jaccard similarity (q< 0.01) and Bray-Curtis dissimilarity (q< 0.05). When considering phylogeny, differences were observed in the high zinc group (q< 0.001), as shown in unweighted and weighted UniFrac measures. The presence of ARG will be analyzed using shotgun metagenomic sequencing and innate immunity will be evaluated using intestinal barrier and inflammatory biomarkers. Conclusions: The preliminary data shows that trace metal supplementation plays a role in the presence and abundance of microbial communities, with dietary zinc having a distinct effect on phylogenetic diversity. Further analysis will elucidate the relationship between trace metals, host immunity, and the onset of ARG in gut bacteria during enteric infection. Funding Sources: Rustici Nutrition Seed Grant and Novo Nordisk Foundation.