8/11/2019 H_Pylori: poster

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Treatment ofH. pyloriClinical outcomes of infection

Infection

Risk factors for gastric cancer

EnvironmentalSmokingDiet high in saltDiet low in fresh fruit and vegetablesIron deficiency

Host geneticsGenes associated with increased risk of H. pyloriinfection: TLR1Genes associated with increased risk of gastric cancer: IL1B, TNF, IL8, PSCA

Bacterial

Photo

Photo

H. pyloriare spiral-shaped Gram-negative bacteria with polarflagella that can survive in the human gastric mucosa. Thebacteria have evolved intricate mechanisms to avoid thebactericidal acid in the gastric lumen and to survive near to,to attach to, and to subvert the human gastric epitheliumand immune system.

Diagnosis ofH. pylori

Noninvasive (preferred)

Serology: IgG against H. pylori

Stool antigen test

Breath test for diagnosis of H. pyloriinfection

Invasive (requires endoscopy)

Histology: gastric biopsy samples stained for H. pyloriusing haematoxylin and eosin, immunohistochemistry, silver staining, Genta stain or alcian yellowtoluidine blue

Culture of gastric biopsy samples

Rapid urease test

If H. pyloriis present, urea isconverted into ammonia andcarbon dioxide by their ureaseenzymes. The breakdown of ureaincreases the pH level of thesolution, triggering a colourchange from yellow to pink.

H. pylori

positive

H. pylori

negative

Urea and pHindicator(e.g. phenol red)

Biopsy samples fromthe stomach antrum

The patient is given a drinkcontaining urea labelled withnonradioactive carbon-13.If H. pyloriis present, their ureaseenzyme breaks down urea to form

carbon dioxide, which is exhaled.After taking the urea-based drink,the patient blows into the sampletube or bag which is then testedfor an increase in the proportionof carbon dioxide containingcarbon-13. A positive resultindicates presence of H. pyloriand the appropriate eradicationtherapy can then be prescribed.

Tailored Rx

Available

H. pyloriinfection

History of antibiotic use? Previously treated for H. pylori?

Susceptibility testing

Not available

Current available drugs

13C Urea

UreaseCO2+

NH3

13CO2in blood

13CO2in breath

In the USA, the prevalence of resistance is ~15% to clarithromycin and 25% to metronidazole, but is much higherin individuals who have taken those antibiotics for other infections. If susceptibility of the pathogen is known , anumber of regimens will be effective. If not, the preferred regimens in Western countries are 14-day concomitanttherapy and 1014 day bismuth-quadruple therapy. Choice depends on patient and physician preference andspecific allergies or interactions with other d rugs the patient is taking. As failure does not stop progression ofthe disease and treatment failures are common, a noninvasive test for cure is recommended.

All consensus statements agree that wheneverH. pyloriis diagnosed it should be cured if possible.H. pylorieradication reduces gastric cancer risk. In regions where gastric cancer is common, such as Japan, it is prudentto also assess gastric cancer risk to ascer tain whether marked risk remains and, thus, whether surveillance forsubsequent gastric cancer might be indicated.

Antibiotic regimen* Clarithromycin Amoxicillin Metronidazole PPI Tetracycline Bismut h LevofloxacinConcomitant (14 days)

Hybrid (14 days)

Days 17

Days 814

Bismuth (1014 days)

Clarithromycin (14 days)

Sequential(14 days)

Days 17

Days 814

Levofloxacin||(14 days)

*All regimens are useful as tailored therapies when treating based on known antibiotic susceptibility patterns. Limited to low clarithromycin-resistanceareas (