Helicobacter pylori Bacteria
The ability of the Helicobacter pylori bacteria to cause peptic ulcer was first discovered by an Australian physician in 1982. The doctor cultured a microaerophilic, spiral-shaped bacterium observed in a biopsied tissue of a stomach ulcer patient. He ascertained that the bacterium has the ability to hydrolyze the stomach cells and actually create ulcer. The bacterium is now called Helicobacter pylori, and it is accepted that this bacteria is accountable for most peptic ulcer cases. Peptic ulcer disease affects the gastric lining of the stomach and the duodenum, the upper portion of the small intestine.
It is estimated that 30-50% of the population of first world countries is infected with the Helicobacter pylori bacteria. However, only 15% of the said figure develops the ulcer signifying that some host factors are somewhat involved. For example, researchers found that type O people are more susceptible for the disease. There are also studies saying that H. pylori cause gastric cancer.
How Helicobacter Pylori Bacteia Creates an Ulcer
Anatomically speaking, the stomach mucosa has cells that produce gastric juice containing proteolytic enzymes and hydrochloric acid that stimulates these enzymes to do their job. We can also see other specialized cells in the mucosa; these cells secrete a layer of mucus that prevents the stomach from digesting itself. Disruption of this protective layer of mucus would result to gastritis or stomach inflammation. This inflammation could then advance to an ulcerated area.
While the acidic environment of the stomach is considered lethal to most bacteria, H. pylori have an adaptive mechanism in surviving to such environment. It secretes great amount of urease, an enzyme capable of converting urea to the alkaline compound ammonia, resulting to the increase in pH in the region of growth.
Biopsy of stomach tissue and culture of the organisms is the most reliable diagnostic test. Scientists have developed this interesting diagnostic method called Helicobacter pylori breath test. In this test, the patient would swallow radioactivity-labeled urea, and after 30 minutes, his breath will be analyzed for the presence of radioactivity-labeled carbon dioxide. If radioactive carbon is present, the patient has H. pylori in his stomach. (Note that the CO2 is produced when the bacterial urease converts urea to ammonia.)
After the patient is found positive in the test, he would be requested to submit some samples of his stools to detect H. pylori antigens. There are also inexpensive serological tests to detect bacterial antibodies but less specific.
There are now anti-microbial drugs against H. pylori. Some antibiotics have proven effective when they are taken in combination. Bismuth subsalicylate (Pepto-Bismol) is proven effective and the most preferred among the drugs. There is an annual recurrence rate of 2-4% after the bacteria are totally eradicated. Reinfection is often times the result of poor environmental sanitation. Actually, the disease is slowly disappearing in developed countries where the standard of sanitation is high.
Prescott, Lansing.2002. Microbiology. New York : McGraw-Hill