H. pylori Flashcards
(14 cards)
What is duodenal ulcer disease?
when the first part of the surface of the duodenum becomes eroded by gastric acid
Describe the epidemiology of duodenal ulcer disease
- more common in males
- more common in smokers
1-5% pop
What is the outcome of duodenal ulcer disase?
o Constant pain
o Ulcer erodes deep enough to hit major blood vessels causing massive upper gastric haemorrhage
>Vomiting of blood and passing blood in stool can be fatal
o Gastric acid might enter peritoneum causing acute peritonitis
Describe the regulation of acid secretion
Vagal stimulation causes parietal cells to secrete acid
Gastric phase food entry stimulates G cells to secrete gastrin
Negative inhibition controls amount of acid produced
o Build-up of acid inhibits G cells, preventing further gastrin release (G cells are indirectly inhibited
via D cells, which are inhibited - preventing somatostatin release)
o G cells are located in glands in distal part of stomach
What surgical procedure were used in duodenal ulcers?
Vagotomy used to be very common – cut vagus nerve to reduce acid production
o This did not treat the root cause
What medications are used in controlling duodenal ulcers?
o H2 receptor antagonists blocked ability of parietal cells to produce acid (by preventing the action
of histamine)
o PPIs acted directly on parietal cells to inactivate proton pump – much more effective than H2
antagonists
How does H. pylori survive in the stomach?
H pylori has a very high urease enzyme activity
o Breaks down urea to ammonium and bicarbonate = strong alkali
Bacteria creates a strong cloud of alkali between its inner and outer membranes, allowing it to grow in
very acidic conditions
How can duodenal ulcers be cured?
Eradication of H pylori with antibiotics was found to permanently cure DU
What is the mechanism behind increased gastrin release?
Bacterium neutralises acid
h pylori is found near the G and D cells (which sense acid levels), these cells maintain acid secretion because the bacteria confuses them as to how acidic the stomach is
(Like putting ice right on top of a thermostat)
H. pylori deregulates the amount of acid produced in the stomach, leading to excess acid production
What are the first line medications used in the treatment of H.pylori infection?
o Omeprazole 40mg Mane
o Metronidazole 400mg TDS
o Amoxycillin 500mg TDS
What are the second line medications used in the treatment of H.pylori infection?
o Omeprazole 40mg Mane
o Clarithromycin 500mg TDS
o Amoxycillin 500mg TDS
What are the third line medications used in the treatment of H.pylori infection?
o Omeprazole 40mg Mane
o Metronidazole 400g BD
o Clarithromycin 500g BD
What are the possible outcomes of H. pulori infection?
> 50% general population have H.pylori
> 80% No associated disease
5-15% Peptic Ulcer Disease
1-3% Gastric Cancer
NB: H. Pylori is a necessary, but not sufficient factor for noncardia gastric cancer
Which patients are at risk of gastric cancer?
When inflammation and infection cause atrophic gastritis, parietal cells, G cells and other cells are
destroyed, and gastric acid secretion decreases significantly
These are the individuals with a very high risk of developing stomach cancer
