Helicobacter pylori

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Helicobacter pylori



Helicobacter pylori


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USMLE® Step 1 questions

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High Yield Notes

6 pages


Helicobacter pylori

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USMLE® Step 1 style questions USMLE

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A group of researchers is evaluating the association between bacteria and peptic ulcer disease. A bacterial species is isolated, and its enzymatic makeup and other laboratory characteristics are studied. Which of the following bacteria features can be used in the diagnosis?  

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Helicobacter pylori p. , 144


Helicobacter pylori p. , 144

Gastric adenocarcinomas

Helicobacter pylori p. , 144

Gastritis p. 388

Helicobacter pylori p. , 144

Helicobacter pylori p. , 144

associations p. 727

catalase-positive organism p. 125

disease association p. 388

Gram-negative algorithm p. 139

metronidazole p. 192

as oncogenic microbe p. 223

penicillins for p. 185

silver stain p. 123

urease-positive p. 125

urease-positive organism p. 125

MALT lymphomas

Helicobacter pylori p. , 144

Metronidazole p. 192

Helicobacter pylori p. , 144

Peptic ulcer disease p. 389

Helicobacter pylori p. , 144

Proton pump inhibitors (PPIs) p. 407

for Helicobacter pylori p. , 144


Helicobacter pylori p. , 144


Content Reviewers

Helicobacter pylori, or H. pylori for short, is a bacterium found in the stomach of over half of the world’s population.

In some individuals it can cause inflammation of the stomach lining; and can result in peptic ulcers.

In fact, complications from H. pylori ulcers is thought to have been the cause of death for the famous writer, James Joyce.

H. pylori is a gram-negative bacteria that’s shaped like a curved rod and it has 2 to 6 flagella, kind of like multiple tails, all at one end which it uses for movement.

It’s positive for urease, oxidase and catalase; and is a microaerophile, so that means it needs oxygen to survive, but requires less than the levels typically found in the atmosphere.

Now in the stomach, there are four regions - the cardia, the fundus, the body, and the pylorus.

And the pylorus itself is made up of two main parts: the antrum; and the pyloric canal, which connects to the first section of the small intestines called the duodenum.

Ok, now normally, the inner wall of the entire gastrointestinal tract is lined with mucosa, which consists of three cell layers.

The innermost layer is the epithelial layer and it absorbs and secretes mucus and digestive enzymes.

The middle layer is the lamina propria and it has blood and lymph vessels.

The outermost layer of the mucosa is the muscularis mucosa, and it’s a layer of smooth muscle that contracts and helps with the break down food.

The epithelial layer dips down below the surface of the stomach lining to form gastric pits.

And these pits are contiguous with gastric glands below which contain various epithelial cell types - each secreting a variety of substances.

So for example, foveolar cells, or surface mucus cells, secrete mucus, which is a mix of water and glycoproteins that coats the stomach epithelial cells.

With all of these digestive enzymes and hydrochloric acid floating around, the stomach and duodenal mucosa would get digested if not for this mucus which coats and protects the epithelial cells.

Within the glands, particularly in the body and fundus of the stomach, are parietal cells, which secrete hydrochloric acid to help maintain an acidic pH in the stomach.


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