Helicobacter Pylori

WHAT IS IT?

Helicobacter pylori (H. pylori): is a curved gram negative rod bacterium.

Visual appearance of H. pylori on an H&E slide (source)
Visual appearance of H. pylori on an H&E slide (source)

Sliver stain can be used for this bacterium.

Silver stain of H. pylori on epithelial cells (source)
Silver stain of H. pylori on epithelial cells (source)
CULTURE CHARACTERISTICS 

Catalase positive: bubbles observed when bacteria are added to hydrogen peroxide

Oxidase positive: a redox indicator will be turned dark blue when oxidized indicating that the bacterium produces cytochrome c oxidases.

Visual appearance of one form of the oxidase test. A displays an oxidase positive bacteria, and B is the oxidase negative (source)
Visual appearance of one form of the oxidase test. A displays an oxidase positive bacteria, and B is the oxidase negative (source)
MOLECULAR CHARACTERISTICS 

Urease positive: this bacteria produces urease that creates an alkaline environment. A urea breath test can be diagnostic for H. pylori colonization.

Antigens excreted in the feces can be used as a diagnostic test as well.

TRANSMISSION

Oral ingestion seems to be the means by which this bacteria is transmitted.

CONDITIONS CAUSED

Gastrointestinal conditions can be caused by this bacteria which include:

  • Gastritis (Type B, in the second part of the stomach/antrum)
  • Peptic ulcers (leading cause of duodenal, second biggest cause of gastric behind NSAID use)
  • Gastric cancer (adenocarcinoma)
  • MALT lymphoma/Marginal Zone lymphoma
TREATMENT 

Triple therapy (for H. pylori infection + ulcers) is a common treatment regimen that includes

  1. Proton pump inhibitor (omeprazole): this medication irreversitbly inhibits the H+/K+ ATPase pump in stomach parietal cells, reducing the pH in the stomach.
  2. Clarithromycin
  3. Amoxicillin: (metronidazole can be used if penicillin allergy)
OTHER HY FACTS

Gastrin is a GI regulatory substance (which is responsible for proton secretion into the stomach) is increased in chronic atrophic gastritis (that can be caused by H. pylori)

 

Page Updated: 05.10.2016