Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2008
Publication Date: 11/4/2008
Citation: Edrington, T.S., Farrow, R.L., Sperandio, V., Hughes, D.T., Lawrence, T.E., Callaway, T.R., Anderson, R.C., Nisbet, D.J. 2008. Acyl-homoserine-lactone autoinducer (AHL) in the gastrointestinal tract of feedlot cattle and correlation to season, E. coli 0157:H7 prevalence and diet. Current Microbiology. 58:227-232.
Interpretive Summary: Cattle and sheep are naturally infected with E. coli 0157:H7, a bacteria that causes food sickness in humans. Recent research has attempted to understand E. coli 0157:H7 colonization in cattle. Acyl-nomoserine-lactone (AHL) autoinducers are produced by other bacteria and are thought to be required by E. coli 0157:H7 to become established in the intestinal tract of cattle. It is unknown what effect diet, season, or location within the gastrointestinal tract has on AHL prevalence. Therefore, we sampled multiple sites in the gastrointestinal tract of feedlot cattle in the fall, winter, spring, and summer for AHL determination. We also sampled sheep and cattle, fed either all forage or high grain diets, to determine effect of diet on AHL. Results of the studies indicate that AHL are found only in the rumen of cattle and that type of diet is an influence on concentration, but not prevalence of AHL. Additionally, AHL were found in rumen samples collected in the spring, summer, and fall, but not in the winter. Results of this research may contribute to the understanding of mechanisms required for E. coli 0157:H7 colonization in cattle.
Technical Abstract: Acyl-homoserine-lactone autoinducer (AHL) produced by non-enterohemorrhagic E. coli (EHEC) species in cattle appears to be required for EHEC colonization of the gastro¬intestinal tract (GIT). The objectives of the current research were to examine the effect of season, diet, EHEC shedding, and location within the GIT on AHL prevalence in the ruminant. Luminal content samples were collected from the rumen and rectum of feedlot cattle at slaughter in the spring, summer, fall, and winter for culture of E. coli 0157:H7 and AHL determination. During the spring collection, samples were additionally collected from the cecum and small intestine; however, these samples were all AHL negative, and therefore, were not examined again. To assess the influence of diet on AHL prevalence, fourteen lambs were fed either 100% forage or 80% concentrate diets and experimentally inoculated with EHEC. Eight days following infection, all lambs were euthanized, necropsied, and luminal contents collected from the GIT. Rumen fluid samples were additionally collected from cattle fed either all forage or high concentrate diets. Results of the collections from feedlot cattle found AHL in 100% of the rumen content samples from the spring, summer, and fall, but not in any of the samples from the winter collection. No other GIT samples from feedlot cattle were AHL positive, and all of the samples from the sheep study were AHL negative. In cattle, there appeared to be a weak correlation between ruminal AHL and EHEC prevalence, which was not influenced by diet.