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24 Cards in this Set

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what is the basic biology of helicobacter pylori?
gram neg spiral, oxidase pos, motile with 4 to 6 polar flagella, microaerophilic and fastidious, urease positive, survives acid environment of stomach
where does pylori live and infect in the human?
in the antrum of the stomach, sometimes the corpus/body. It does not like the body bc the gastric pits there produce more acid whereas the pits in the antrum do not
what diseases are caused by pylori?
non ulcer dyspepsia (heart burn), gastritis, gastric ulcers, duodenal ulcers, MALT lymphoma (B cell lymphoma), gastric adenocarcinoma.... may also cause heart and liver disease, glaucoma, raynauds and some other crap
what kind of gastritis from pylori can cause gastric ulcers, cancer, and lymphoma? duodenal ulcers?
chronic and multi atrophc gastritis (pan gastritis into the corpus) as well as intestinal metaplasia. non atrophic gastritis.
T/F:
1. pylori is a group I carcenogen.
2. is one class below smoking in carcenognes.
3. only bac that is a carcinogen.
1.T 2. F 3. T
what are the symptoms most commonly seen in pylori infections?
most are asymptomatic, dyspepsia but all strains cause gastritis, upper ab pain, weight loss, loss of apetite. Note that these are all non specefic and could be many things
after adhering to the gastric epi cells, what does pylori do?
stimulates these cells to produce IL-8 chemokine which is a major chemotactic factor for neutros, on histo may see neutros, then lymphos and maybe a follicle
what is the progression to gastric cancer in pylori?
infection - neutros- superficial gastritis (non atrophic) - less acid, diet of host changes, gastric pits are damaged - chronic atrophic gastritis - intestinal metaplasia - dysplasia - cancer
what does the virulence factor urease do for the bug and how can we utilize it?
breaks down urea into ammonia and CO2 thus neutralizing the stomach, most abundant protein in helico, urease neg mutants are avirulent, it is highly immunogenic and is a good vaccine candidate, also is used to diagnose it
what are all the virulence factors?
multiple adhesins and receptors, urease, pathogenicity island, VacA toxin, CagA protein, flagella
what gene/virulence factor is found on a pathogenecity island of about 50% of bacs?
CagA
how does the CagA virulence factor enter and effect the host?
injected into epi cell via type IV and some other strange and complicated mechanisms, it is from a pathogenecity island, and it causes the improved colonization of the corpus and thus more spread gastritis leading to cancer and ulcers
what does the VacA autotransporter virulence factor do?
vacuolating cytotoxin which disrupts the mitos leading to apoptosis and thus inhibits T cell proliferation
T/F
H. pylori strains are highly heterogeneous and hyper variable.
T
describe the epidemiology of pylori.
2nd most common bac infections in humans, 50% infected worldwide, usually underdeveloped countries, prevalence increases with age.
what country has the highest rate of gastric cancer in the world?
Japan
what factors are associated with gastric cancer?
poor drinking water, low SEC, smoking, salt, smoked foods, nitrates, complex carbs but NOT vit A,C, veggies, fruits, fiber
what role may pylori have in esophigeal cancer?
it may actually have a preventative role
what happens to MALT lymphoma if H. pylori is eradicated?
the cancer goes away.
describe the transmission of pylori.
it is not well understood, fecal oral is most likely bc countries with poor drinking water have higher risk. oral oral via vomit may be... strangely family members with one strain will pass that strain on to others in the family but we do not know why. PPl may be infected with multiple strains, invivo recombination between strains also can occur
what are the non invasive ways to test for pylori?
serology tests (not recommended bc very low speceficity and sensitivity), urea breath test (uses radioactive urea, but also sees other helicobacter species) and stool antigen test, rapid urease test, histology
describe the invasive tests to diagnose pylori.
histo and culture via endoscopic biopsy will give definitive diagnosis. Rapid urease test detects presence of ammonia via a pH indicator but all helicobacters are positive.
what are the treatments for pylori and what diseases do they get rid of?
proton pump inhibitor to block acid so antibiotics work better + clarithromycin + amoxicillin (preferred) or metronidazole or tetracycline. Reverses ulcers, gastritis, MALT lymphoma but not cancer. NOTE there is resistance to metronidazole and clarithromycin but not much to amoxil
what is the major theory behind treatment failures of pylori?
it is believed it can now go intracellular to avoid antibiotics