Sunday, April 10, 2011

Helicobacter pylori: The Cause of Peptic Ulcers

Approximately one-sixth of the world's population suffers from stomach (peptic) ulcers caused by the hard to treat microbe, Helicobacter pylori (H. pylori). A peptic ulcer is a sore on the lining of the stomach or the duodenum. A common misconception of ulcers are that they come from stress or eating spicy foods, but it is H. pylori that cause these painful sores. The bacterium causes peptic ulcers by damaging the mucous coating that protects the stomach and duodenum. When the mucous coating is damaged it then allows stomach acid to get to the sensitive lining beneath. H. pylori is thought to be obtained through food that has not be washed well or cooked properly or from drinking water that has come from an unclean source. It is also thought that an infected person can spread the bacterium to an uninfected person. Although researchers are still unclear how this works it is thought that it can be passed by an uninfected person coming in contact with the stool or vomit of an infected person. It is also thought that it can be passed through the direct contact of saliva.

If a person is thought to have a peptic ulcer caused by H. pylori a doctor can do three noninvasive tests to test for the bacterium. The first is a blood test that checks for H. pylori antibodies. The second is a urea breath test. The patient swallows a capsule, liquid, or pudding that contains urea labeled with a specific carbon atom. After a few minutes the patient breathes into a container, exhaling carbon dioxide. If the carbon atom is found in the breath then H. pylori is present. This is because the bacterium contains a large amount of urease. The third test is a stool antigen test which tests for H. pylori antigens in the patient's stool.

To kill the H. pylori researchers have found that they need to block a key chemical pathway that the bacteria needs for survival. Flabodoxin, a key protein that H. pylori needs for survival, happens to be what needs to be blocked. However, the problem is that H. pylori eaisly becomes resistant to certain antibiotics. Sancho and his team screened 10,000 chemicals for their ability to block flavodoxin and only identified four that showed promise. Three of the four substances killed the bacterium and did not have any apparent toxic effects in lab animals. It is now believed that in order to get rid of H. pylori the antibiotic clarithromycin, a PPI, and the antibiotics amoxicillin or metronidazole for 10 to 14 days will do the trick.

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