Transcriptional analysis reveals specific niche factors and response to environmental stresses of enterohemorrhagic Escherichia coli O157:H7 in bovine digestive contents.

Background: Enterohemorrhagic Escherichia coli (EHEC) are responsible for severe diseases in humans, and the ruminant digestive tract is considered as their main reservoir. Their excretion in bovine feces leads to the contamination of foods and the environment. Thus, providing knowledge of processes used by EHEC to survive and/or develop all along the bovine gut represents a major step for strategies implementation.

Transcriptomic analysis reveals specific metabolic pathways of enterohemorrhagic Escherichia coli O157:H7 in bovine digestive contents.

Background: The cattle gastrointestinal tract (GIT) is the main enterohemorrhagic Escherichia coli (EHEC) reservoir. In order to identify nutrients required for the survival or multiplication of EHEC in the bovine GIT, we compared the transcriptomes of the EHEC O157:H7 reference strain EDL933 cultured in vitro in bovine digestive contents (DCs) (rumen, small intestine and rectum) using RNA-sequencing.

Results: Gene expression profiles showed that EHEC EDL933 activated common but also specific metabolic pathways to survive in the different bovine DCs.

Aspartate metabolism is involved in the maintenance of enterohaemorrhagic Escherichia coli O157:H7 in bovine intestinal content.

The gastrointestinal tract (GIT) of healthy cattle is the main reservoir of enterohaemorrhagic Escherichia coli (EHEC). Therefore, it is crucial to better understand the physiology of EHEC in the bovine GIT. In this study, we demonstrate that aspartate present in bovine small intestine content (BSIC), was exhausted after incubation of the reference EHEC strain EDL933 but was poorly assimilated by the endogenous microbiota.

Factors Involved in the Persistence of a Shiga Toxin-Producing O157:H7 Strain in Bovine Feces and Gastro-Intestinal Content.

Healthy cattle are the primary reservoir for O157:H7 Shiga toxin-producing responsible for human food-borne infections. Because farm environment acts as a source of cattle contamination, it is important to better understand the factors controlling the persistence of O157:H7 outside the bovine gut. The O157:H7 strain MC2, identified as a persistent strain in French farms, possessed the characteristics required to cause human infections and genetic markers associated with clinical O157:H7 isolates.

Lactobacillus reuteri suppresses E. coli O157:H7 in bovine ruminal fluid: Toward a pre-slaughter strategy to improve food safety?

The bovine gastrointestinal tract (GIT) is the main reservoir for enterohaemorrhagic Escherichia coli (EHEC) responsible for food-borne infections. Therefore, it is crucial to develop strategies, such as EHEC suppression by antagonistic microorganisms, to reduce EHEC survival in the GIT of cattle and to limit shedding and food contamination. Most human-derived Lactobacillus reuteri strains produce hydroxypropionaldehyde (HPA), an antimicrobial compound, during anaerobic reduction of glycerol.

Colonization of the meat extracellular matrix proteins by O157 and non-O157 enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) are anthropozoonotic agents that range third among food-borne pathogens respective to their incidence and dangerousness in the European Union. EHEC are Shiga-toxin producing E. coli (STEC) responsible for foodborne poisoning mainly incriminated to the consumption of contaminated beef meat.

NsrR, GadE, and GadX interplay in repressing expression of the Escherichia coli O157:H7 LEE pathogenicity island in response to nitric oxide.

Expression of genes of the locus of enterocyte effacement (LEE) is essential for adherence of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelial cells. Gut factors that may modulate LEE gene expression may therefore influence the outcome of the infection. Because nitric oxide (NO) is a critical effector of the intestinal immune response that may induce transcriptional regulation in enterobacteria, we investigated its influence on LEE expression in EHEC O157:H7.

Carbohydrate utilization by enterohaemorrhagic Escherichia coli O157:H7 in bovine intestinal content.

The bovine gastrointestinal (GI) tract is the main reservoir for enterohaemorrhagic Escherichia coli (EHEC) responsible for food-borne infections. Characterization of nutrients preferentially used by EHEC in the bovine intestine would help to develop ecological strategies to reduce EHEC carriage. However, the carbon sources that support the growth of EHEC in the bovine intestine are poorly documented.