Screening the Ability of Common Feed Ingredients to Reduce Enterotoxigenic Escherichia coli (ETEC) K88 Attachment to Porcine Epithelial CELLS

The purpose of this study was to evaluate the potential of the feed ingredients commonly used in diets, and different kinds of cereal brans, to attach ETEC K88 (adhesion test; AT) and to reduce the attachment to intestinal porcine epithelial cells (IPEC-J2) (blocking test; BT) in vitro. Tested ingredients included different cereals (wheat, oat, rye and corn), protein vegetable ingredients (extruded soybean; soybean meal; rapeseed meal), animal protein ingredients (milk powder, casein glycomacropeptide and fish meal) and different sources of cereal brans (wheat, spelt, kamut, rye, oat and rice). All ingredients were finely ground, res-suspended in phosphate buffer saline (PBS) (1:10 (w/v)) vortex and sonicated three times and then centrifuged. The soluble extracts obtained from the supernatant were used in the AT and BT assays. The tests consist in a miniaturized in vitro system based on high-binding polystyrene microtitration plates.

All cereal grains had the ability to adhere ETEC K88 (P <0.05) in the AT compared to PBS. Regarding the protein vegetable ingredients, rapeseed did not adhere ETEC K88, but the extruded soybean and soybean meal attached specifically to ETEC K88 while they did not recognize the non-fimbriated (NF) E. coli. Milk powder was the only protein source from animal origin that showed the ability to attach ETEC K88 while any effect was observed with fish meal compared to PBS. All cereal brans evaluated attached ETEC K88 compared to PBS (P <0.001).

Rye and oat reduced the attachment of ETEC K88 to IPEC-J2 cells (P < 0.01) in the BT. Wheat soluble extract also had the ability to reduce the attachment of ETEC K88 (P = 0.05). Casein glycomacropeptide, included as positive control in the BT, showed the higher inhibition ability of ETEC K88 attachment to IPEC-J2 (P < 0.001). All cereal brans, with the exception of rice bran, reduced the attachment of ETEC K88 to IPEC-J2 cells (P < 0.001). No difference was observed neither in the AT with any of the tested ingredients evaluated regarding the NF E. coli or the BT suggesting that the recognition of the soluble extracts to the pathogenic bacteria may be due to the fimbria.

Results from these experiments may suggest some cereals like rye, oat and wheat in addition to their brans, should be further evaluated to ascertain the chemical structure involved recognizing ETEC K88 as a tool to prevent colibacilosis induced diarrhea in weaned piglets.