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Lifestyle Influences on the Microbiome
Published in David Perlmutter, The Microbiome and the Brain, 2019
This impact can even be seen on a molecular level. The interbacterial communication system known as quorum sensing (QS) utilizes hormone-like compounds referred to as inducers to regulate bacterial gene expression. Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is responsible for outbreaks of bloody diarrhea. Sperandio and colleagues showed that exogenous epinephrine is an inducer of the 0157:H7 virulence factor.126 EHEC growing in a stressed host may be more virulent than in a non-stressed host.
Infectious Colitis
Published in John F. Pohl, Christopher Jolley, Daniel Gelfond, Pediatric Gastroenterology, 2014
Hemolytic uremic syndrome (HUS) is a clinical triad of simultaneous micro-angiopathic hemolytic anemia, thrombocytopenia, and acute renal injury. Mortality rate can exceed 50%, making HUS a feared complication of infectious colitis. It is an unusual complication of Shiga toxin-producing strains of enterohemorrhagic Escherichia coli (EHEC), occurring in <10% of infections. Shigella species also cause HUS, primarily in southern Africa, India, and Bangladesh. HUS should be suspected in any child with a diarrheal illness who is experiencing oliguria, hematuria, bruising, or petechiae. Symptoms classically begin 5–10 days after the onset of diarrhea, but can be delayed by several weeks. Antibiotics or antimotility drugs given during a diarrheal illness do not decrease the risk of HUS, do not shorten the duration of a diarrheal illness, and have been identified as a risk factor for HUS in the case of EHEC (O157:H7). Stool culture is not part of the diagnostic criteria. Few children with EHEC develop HUS, and perhaps only one-half of HUS patients have positive stool cultures. This stresses the importance of clinical evaluation and outpatient follow-up rather than unnecessary anxiety or inappropriate reassurance from positive or negative cultures.
EspH interacts with the host active Bcr related (ABR) protein to suppress RhoGTPases
Published in Gut Microbes, 2022
Rachana Pattani Ramachandran, Ipsita Nandi, Nir Haritan, Efrat Zlotkin-Rivkin, Yael Keren, Tsafi Danieli, Mario Lebendiker, Naomi Melamed-Book, William Breuer, Dana Reichmann, Benjamin Aroeti
Enteropathogenic Escherichia coli (EPEC), one of the most important human diarrheagenic bacterial pathogens, infects people mainly in low and middle-income countries.1 In contrast, the closely related enterohemorrhagic Escherichia coli (EHEC), which causes hemorrhagic colitis and hemolytic uremic syndrome in humans, is prevalent mainly in the industrial world.2,3Citrobacter rodentium (C. rodentium), a natural mouse pathogen that employs similar strategies of colonization and pathogenesis, serves as an in vivo model for studying EPEC and EHEC infection.4 Following attachment to the host cell surface, these pathogens utilize the type III secretion system (T3SS) to introduce bacterial proteins, termed ‘effector’ proteins, into the host cells.5,6 These effectors specifically target and manipulate host cell organelles and signaling pathways, leading to intimate binding of the bacteria to host enterocytes via the attaching and effacing (A/E) lesion formation,7 modulation of host cell death pathways,4,8 and inhibition of host immune responses.9 Recent in vivo studies using the C. rodentium model have shown that effectors act as a multifunctional and interconnected network within the host cells. These characteristics are essential for inducing the diarrheal disease.10,11
Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7
Published in Gut Microbes, 2022
Hongmin Sun, Min Wang, Yutao Liu, Pan Wu, Ting Yao, Wen Yang, Qian Yang, Jun Yan, Bin Yang
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen that causes severe diseases, including diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUC).1,2,3 It has three major virulence factors, including Shiga toxins (Stxs), products of the pathogenicity island called the locus of enterocyte effacement (LEE), and products of the large virulence plasmid pO157.4 Stxs are bacteriophage-encoded AB5 family toxins that cause damage to a variety of cell types and have often been associated with HC and the lethal hemolytic uremic syndrome (HUS) in humans.5 LEE consists of five polycistronic operons (LEE1 to LEE5) encoding a type III secretion system and associated effectors and enables the bacteria to intimately adhere to host epithelial cells.4 pO157, a highly conserved non-conjugated plasmid with a size ranging from 92 to 104 kb,6 is known to harbor several genes involved in the pathogenesis of EHEC O157:H7 infections, including etpC-etpO, ehxA, toxB, katP, espP, and stcE .7
Apyrase decreases phage induction and Shiga toxin release from E. coli O157:H7 and has a protective effect during infection
Published in Gut Microbes, 2022
Ida Arvidsson, Ashmita Tontanahal, Karl Johansson, Ann-Charlotte Kristoffersson, Sára Kellnerová, Michael Berger, Ulrich Dobrindt, Diana Karpman
Enterohemorrhagic Escherichia coli (EHEC) cause diarrhea, hemorrhagic colitis, and in certain cases the severe complication hemolytic uremic syndrome (HUS)1 characterized by nonimmune hemolytic anemia, thrombocytopenia, and acute kidney injury with up to 5% mortality. There are no specific or effective treatments for this infection and antibiotic treatment, during the prodromal pre-HUS phase, may increase the risk of developing HUS.2E. coli O157:H7 is the most common clinical isolate of EHEC.1 EHEC infects via oral intake of contaminated food or water and is a noninvasive bacterium.3 After ingestion EHEC colonize the intestine.4 In the intestine, EHEC release virulence factors such as Shiga toxin (Stx).5 During human EHEC infection Stx can be found within intestinal cells6 and massive intestinal inflammation and apoptosis have been reported.7 Similarly, mice inoculated intragastrically with EHEC exhibit goblet cell depletion,8 intestinal inflammation, and apoptosis particularly associated with the presence of Stx.7