Gastrointeritis Flashcards
What is the mechanism of Shigella and EIEC pathogenesis
They can induce membrane ruffling of M cells and then escape macrophage killing, will then infect the underside of enterocytes. They can then induce death of enterocytes releasing shiga toxin which can promote death of endothelial cells and heamorrhage. Also HUS can be caused
What is the mechanism of EPEC
Will adhere using the Tir/Intimin adhesion and insertation through the type III secretion system. Will then mediate destruction of cells via manipulation of actin and membrane cytoskeleton. Can also manipulate ion channels through EspG and EspF
What are the mechanisms of EHEC
Will adhere via Tir/Intimin and type three secretion system. Once it invades cells it can then initiate death and release the shiga toxin to mediate endothelial damage and HUS. Can also cause bleeding due to the destruction it causes the lining of the gut
What are the mechanisms of Campylobactor jejuni
Will relase cytolethal distending toxin to induce death of enterocytes leading to watery and bloody diarrhoea
What are the mechanisms of EAEC
Will form an aggregatory biofilm via adherence factor AAF and dispersin. Can then secrete Pec to promote exfoliation of enterocytes. Adhesions will decrease absorption potential
What are the mechanisms of ETEC/Vibrio Cholera
Most common cause of traveller’s diarrhoea, uses the cholera like toxin to increase the presence of cAMP in the cell and cause the opening of Cl- channels (CFTR). This will cause efflux of water etc Toxin is a AB4 toxin in which thee B4 toxin is essential for movement into the cell and A mediates damage
What are the mechansisms of Clostridium Difficile
It is an overgrowth of the microbiota organism that results from overuse of antibiotics and death of other microbiota. The clostridium will then secrete certain toxins that are important in manipulating Cdc42, Rac an Rho and consequently membrane cytoskeletal rearrangement leading to death
What is the mechanisms of Salmonella Thyphi and hypimurium
Will invade via M cells and then through macrophages. WHen they escape from marcophages will invade through the underside of enterocytes and they will propogate via 2/3WASP and ARP throughout the ccells and to adjoining cells. This can compromise the integrity of the epithelial lining and lead t further invasion. The baccteria can then invade into the blood and cause systemic bacteriaemia or septicaemia
what are some common bacteria that release toxins that cause acute Gastro
Staph, salmonella, clostridium, Bacillus, Vibrio spp, Listeria, virus and ciguatoxin
What are the treatments for gastro
Oral rehydration with glucose and Na+ to work on the Na+/glucose channel. Some bacteria treat with antibiotics such as Cholera, thyphoid fever and clostridium difficile
