Case 2 - H.pylori Flashcards
what is H.pylori
it is a ubiquitous organism that is present in about 50%% of the global population
what does chronic infection with H.pylori cause
atrophic and even metaplastic changes in the stomach, and it has a known association with peptic ulcer disease
what is the most common route of H.pylori infection
either oral to oral or fecal to oral contact
features of the bacteria itself
gram negative, helical or spiral shaped and flagellate
what are the diagnostic tests used for H.pylori
Diagnostic tests include invasive tests such as biopsy urease test, histology or bacterial culture and sensitivity test or noninvasive tests such as urea breath test, stool antigen test and serology
what is the most common histologic pattern of H pylori gastritis
chronic active gastritis with superficial band of lymphoplasmacytic cells with or without neutrophils
what are complications of H.pylori gastritis
gastroduodenal ulcers, atrophy, intestinal metaplasia, gastric cancer and mucosa associated lymphoid tissue (MALT) lymphoma
where do the organisms colonise first
in the antrum first by binding to gastric mucins (TFF1) in a pH dependent manner, the organisms have an affinity for gastric mucous cells but do not attach to small intestinal or other gastric epithelial cell types
what is the ideal pH for bacterial survival
4-8
what is the ideal pH for bacterial growth
6-8
what are the major virulence factors
CagA (cytotoxin associated gene A) and its pathogenicity island (CaG PAI) and VacA (vacuolating cytotoxin A)
facts about CagA and CaG PAI
translocates to the host cytoplasm and binds to the inner surface of the cell membrane
major effects: disrupts tight junctions, provokes pro-inflammatory and mitogenic response
what is VacA
cytochrome C release and activation of proapoptotic factor leading to apoptosis
what is gastric inflammation a result of
H pylori infection mediated upregulation of cytokines
what are the most significant cytokines
CagA PAI mediated induction of NFkB and IL8 secretion
Reactive oxygen species and reactive nitrogen species produced by host gastric epithelial cells
what are the clinical features of h pylori
asymptomatic or mild self limited dyspeptic symptoms with transient hypochlorhydria - acute gastritis
Abdominal pain seen with chronic gastritis with or without peptic ulcer disease
Extra gastrointestinal manifestations: iron deficiency anaemia, idiopathic thrombocytopenia pupura, vitamin B12 deficiency
what is the diagnosis for h pylori
diagnostic test of choice based on active bleeding due to suspected peptic ulcer, use of proton pump inhibitor therapy (PPI), antibiotics and bismuth
what are the different treatments for H pylori
Bismuth quadruple (PPI, bismuth subcitrate, tetracycline and metronidazole) or levofloxacin triple (PPI, levofloxacin, amoxicillin), rifabutin triple (PPI, rifabutin and amoxicillin) (Am J Gastroenterol 2017;112:212)
Decision made based on risk factors for macrolide resistance and the presence of a penicillin allergy
what is chronic antral gastritis
infiltration of lamina propria by plasma cells, lymphocytes and small number of eosinophils seen as a superficial band of inflammation
what is active chronic antral gastritis
when the above is associated with neutrophils; this should prompt a search for organsisms
