Helicobacter Pylori Flashcards
1
Q
Physical description of Helicobacter Pylori
A
- gram negative
- spirillum
- lazy ‘S’
- motile at 37C
2
Q
Description of Helicobacter Pylori
A
- oxidase and catalase
- microaerophile
- acid sensitive(pH 4)
- produces large amounts of urease
3
Q
Clinical presentation of Helicobacter Pylori
A
- chronic infection, no acute symptoms
- colonizes gastric mucosa
- stimulates gastrin production, which stimulates acid production in the fundus
4
Q
Associated issues with Helicobacter Pylori
A
- gastric and duodenal ulcers
- gastric adenocarcinoma
5
Q
Detection of Helicobacter Pylori
A
- serologic test
- gram stain/culture of gastric biopsy
- urea breath test, 14C-urea in and 14Co2 out due to urease
6
Q
Epidemiology of Helicobacter Pylori
A
- 50% people are worldwide carriers
- horizontal transmission person to person
- TLR1 allele
- common clusters suggest common source infection
- middle aged and older patients
- gastritis in GERD patients being treated with PPIs
7
Q
Pathogenesis of Helicobacter pylori
A
- binds to base of mucosal cells where pH is 7.4
- bind to Lewis antigen
- huge amounts of urease buffer pH by forming NH3
- produce a vacuolating toxin, VacA
8
Q
Action of VacA toxin
A
- activated by stomach acid
- binds to sphingomyelin “lipid rafts” in gastric epithelial cells
- insert into cell as selective anion channel
- extensive vacuolation of epithelial cells and release of urea, inhibition of antigen presentation pathways of T cells
9
Q
Cytotoxin CagA
A
- secreted by T4SS
- induce apoptosis in host cells
- potential oncoprotein
- both enhanced by salt
10
Q
Control of Helicobacter Pylori
A
- treatment of bismuth subsalicylate
- tetracycline or macrolide + metronidazole
- treat acid with PPI
