Lecture 11 Helicobacter Pylori I Flashcards
What are the diseases caused by H.Pylori?
Infection is largely asymptomatic but can cause duodenal ulcers or gastric ulcers
In duodenal ulcers H.Pylori causes almost all of them while 70% of gastric ulcers are caused by H.Pylori and the remainder is caused by NSAIDs
H.Pylori is a carcinogen with gastric adenocarcinoma is the 2nd leading cause of cancer deaths
What are the culture characteristics of H.Pylori?
Gram negative, spiral shaped rod Microaerophilic Slow to grow requiring 3-5 days for primary culture from a biopsy Translucent white-grey colonies Urease and Catalase positive
What are the epidemiological factors of H.Pylori infection?
It is the most common chronic bacterial infection with over 50% of the worlds population being infected and this infection being lifelong
It is generally contracted in early childhood and is largely restricted to humans and non-human primates with other species having their own helicobacter species
What are the risk factors for H.pylori infection?
Over-crowded living conditions
Poor hygiene
low social class
high salt diet
What are the features of H.pylori transmission?
It is hard to catch as it cannot survive for long periods outside of the host resulting in it requiring close contact
The exact roue of transmission is unknown
How is H.Pylori diagnosed?
Endoscopy or a Urease breath test are the reliable tests however ELISA based serological tests and stool antigen tests are also available
How is endoscopy able to diagnose H.Pylori?
A tube is placed through the patients throat down to the stomach allowing visual inspection of the tissue
Tissue is collected and there is a 1 week culture period on selective media there is then biochemical test and a histological stain of the biopsy with a silver stain to detect H.pylori
How can the urease breath test lead to a H.Pylori diagnosis?
Radioactive urea is given to patients to drink
If helicobacter is present in the stomach then there will be large amounts of the urease enzyme present which will break this down to CO2 which will be expelled in breath
The breath can be collected in a mylar balloon and the radioactivity can be measured to see if the urease was broken down
How is infection with H.Pylori treated?
A triple treatment is used with the patients being on Amoxicillin/Clarithromycin/Proton pump inhibitor for 2 weeks this treatment is more than 80% effective and recurrence of infection is less than 1% after a successful treatment
How does H.Pylori mediated disease progress?
The patient is infected with H.Pylori
There is superficial active gastritis produced in days- weeks after infection
Chronic Active gastritis occurs over months and years
Depending on the location of the H.Pylori in the stomach antral gastritis, pangastritis and chronic active gastritis may occur over decades
After this duodenal gastric metaplasia, atrophy intestinal metaplasia or chronic active gastritis may develop
The may later cause duodenal ulcers, gastic ulcers and cancer or MALT Lymphoma
What is significant of the co-evolution of helicobacter pylori and man?
H.Pylori seems more likely to cause disease if you are infected with the H.Pylori that does not have the same descent as your own suggesting it may be an amphibiont
What are the potential benefits of H.Pylori infection?
It may decrease inflammatory disease such as asthma, alleriges or inflammatory bowel disease
What is an amphibiont?
A microbe that could be a pathogen or a symbiont depending on context
What is the most likely way people become infected with H.Pylori?
The gastro-oral route
