LAUSR

Objectives Although iron fortification/supplementation is recommended for infants (6 to 12 months) and toddlers by pediatrics, the optimal dose is still largely debated. One of controversies centers on whether iron fortification at recommended dose increases the risk of infection. Using a weanling piglet model, we aim to assess the dose of iron fortification on host susceptibility to enterotoxigenic E. coli (ETEC) infection. Methods Thirty-two weanling piglets were randomly assigned to four treatments on PD21, including normal iron diet (250 mg/kg) without ETEC challenge (CON), and Low (125 mg/kg; LOI), normal (COI), or high iron (750 mg/kg; HII) diets with ETEC challenge. On study day 10 (d10), piglets were orally inoculated with 1010 cfu/dose of F18 ETEC once daily for 3 consecutive days. The pathogen colonize in small intestine and cause watery diarrhea in weanling pigs. Piglets were euthanized on d16 for tissue sampling. A 5-scale fecal score were recorded daily. Feces collected on d10, 13 and 16 were plated on blood and MacConkey agars to verify absence or presence of the pathogen. Blood sampled on d0, 10, 13 and 16 were analyzed for hemoglobin, hematocrit, iron and cytokines. Intestinal tissue sections will be stained for iron using Prussian blue and spatial localization of E. coli through fluorescence in situ hybridization. Results The pathogen was absent in feces of all piglets on d10 before inoculation, but was detected at different abundances only in ETEC-inoculated piglets on d13. By d16, only 2 fecal samples from each ETEC-inoculated group were positive for the pathogen, which was accompanied by improved fecal scores. Piglets in LOI suffered more days of diarrhea (fecal score >2) as compared to CON and COI (P < 0.05). Iron content did not affect BW by d10. Nonetheless, piglets in LOI had lower BW (P < 0.05) than those in HII and CON on d16. Hemoglobin was consistently higher in HII than that in COI and LOI. Enteric infection reduced hemoglobin regardless of dietary iron content. Conclusions Our preliminary results showed both iron inadequacy and excess exacerbated ETEC-induced diarrheal illness. However, high iron improved growth during transient ETEC infection in weanling pigs. Funding Sources UC Davis; NIFA.