Case 2 - H.pylori

Question 1

what is H.pylori

Answer 1

it is a ubiquitous organism that is present in about 50%% of the global population

Question 2

what does chronic infection with H.pylori cause

Answer 2

atrophic and even metaplastic changes in the stomach, and it has a known association with peptic ulcer disease

Question 3

what is the most common route of H.pylori infection

Answer 3

either oral to oral or fecal to oral contact

Question 4

features of the bacteria itself

Answer 4

gram negative, helical or spiral shaped and flagellate

Question 5

what are the diagnostic tests used for H.pylori

Answer 5

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

Question 6

what is the most common histologic pattern of H pylori gastritis

Answer 6

chronic active gastritis with superficial band of lymphoplasmacytic cells with or without neutrophils

Question 7

what are complications of H.pylori gastritis

Answer 7

gastroduodenal ulcers, atrophy, intestinal metaplasia, gastric cancer and mucosa associated lymphoid tissue (MALT) lymphoma

Question 8

where do the organisms colonise first

Answer 8

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

Question 9

what is the ideal pH for bacterial survival

Answer 9

4-8

Question 10

what is the ideal pH for bacterial growth

Answer 10

6-8

Question 11

what are the major virulence factors

Answer 11

CagA (cytotoxin associated gene A) and its pathogenicity island (CaG PAI) and VacA (vacuolating cytotoxin A)

Question 12

facts about CagA and CaG PAI

Answer 12

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

Question 13

what is VacA

Answer 13

cytochrome C release and activation of proapoptotic factor leading to apoptosis

Question 14

what is gastric inflammation a result of

Answer 14

H pylori infection mediated upregulation of cytokines

Question 15

what are the most significant cytokines

Answer 15

CagA PAI mediated induction of NFkB and IL8 secretion
Reactive oxygen species and reactive nitrogen species produced by host gastric epithelial cells

Question 16

what are the clinical features of h pylori

Answer 16

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

Question 17

what is the diagnosis for h pylori

Answer 17

diagnostic test of choice based on active bleeding due to suspected peptic ulcer, use of proton pump inhibitor therapy (PPI), antibiotics and bismuth

Question 18

what are the different treatments for H pylori

Answer 18

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

Question 19

what is chronic antral gastritis

Answer 19

infiltration of lamina propria by plasma cells, lymphocytes and small number of eosinophils seen as a superficial band of inflammation

Question 20

what is active chronic antral gastritis

Answer 20

when the above is associated with neutrophils; this should prompt a search for organsisms