Stomach, Gastric or Peptic Ulcers and Helicobacter pylori
Stomach Bacteria and Ulcers
A bacterium named Helicobacter pylori lives inside the stomach of many people. For some of these people the bacterium causes no noticeable problems. In others it causes inflammation of the stomach lining and produces sores known as stomach ulcers.
Stomach ulcers are also called gastric or peptic ulcers. The term “peptic ulcer” is the general name for an ulcer that occurs in the stomach or in the duodenum, which is the first part of the small intestine. Whatever they're called, ulcers can cause a lot of discomfort and pain.
The lining of the stomach produces hydrochloric acid and digestive enzymes. After a meal, the stomach contains an acidic, churning mass of food and enzymes. We would expect this mixture to be an inhospitable environment for bacteria, but Helicobacter has some useful abilities to enable it to thrive inside the stomach.
Functions of the Stomach
When food is swallowed, it passes down a tube called the esophagus and enters the stomach. The stomach is a J-shaped organ which is located on the left side of the upper abdomen (from the owner's point of view). It’s covered by the liver and has a volume of about one litre when it's empty. After a meal it can expand to around four litres.
When we eat, glands in the lining of the stomach release hydrochloric acid, which makes the fluid inside the stomach acidic. This fluid is known as gastric juice and has a pH of about 2. The pH scale runs from 0 to 14, with the lower numbers indicating more acidic conditions.
Stomach glands also produce a chemical called pepsinogen. When pepsinogen enters the gastric juice it’s converted into an enzyme called pepsin by the hydrochloric acid. The pepsin then begins the digestion of the proteins that have entered the stomach cavity after a meal.
Completion of Digestion
Food generally stays in the stomach for about two to four hours. The mixture of fluid and partially digested food is known as chyme. After the stomach's job is done, chyme is gradually sent into the small intestine to complete its digestion. A muscle called the pyloric sphincter controls the passage of the chyme out of the stomach and into the duodenum.
Food is moved through the esophagus, stomach, small intestine and large intestine by a process called peristalsis. Peristalsis is a series of muscular contractions that travel in waves along the walls of the digestive tract.
Digestion converts food into particles that are small enough to be absorbed through the lining of the small intestine and into the bloodstream. A healthy, undamaged gut lining is very important.
Bacteria in the Stomach
A mucus layer covers the stomach lining to protect it from an acid attack or from an attack by pepsin. The hydrochloric acid kills most bacteria that enter the stomach, but not all of them. Stomach ulcer bacteria, for example, burrow deep into the mucus layer and move towards the stomach lining. Here they are protected from the acid.
Stomach ulcer bacteria make an enzyme called urease, which converts the urea that is present in the stomach fluid into ammonia and carbon dioxide. Ammonia is a base and helps to neutralize any acid which approaches the bacteria. It also helps to disrupt the mucus barrier covering the stomach lining, allowing the bacteria to enter the mucus.
Some other types of bacteria may be able to survive the journey through the stomach if they enter the stomach in large numbers or if they are surrounded by food that temporarily increases the pH of their environment.
The Urea Breath Test for a Stomach Ulcer
The production of carbon dioxide by H. pylori as it breaks down urea is the basis of the urea breath test for stomach ulcers.
During the test, the patient swallows a liquid containing "labeled" urea. The carbon in labeled urea is different from normal carbon in some way so that it can be easily detected. For example, it may have a higher atomic mass than normal carbon. If there are ulcer bacteria in the patient's stomach, the bacterium's urease will produce labeled carbon dioxide from the breakdown of the urea. This chemical will then be sent to the lungs to be exhaled. Labeled carbon dioxide in the patient's breath strongly suggests that ulcer bacteria are present in the stomach.
Other tests to detect a stomach ulcer include the examination of a fecal sample, a blood test, endoscopy to examine the lining of the stomach and a biopsy (the removal of a small piece of the stomach lining for detailed observation).
How Does H. pylori Cause a Gastric Ulcer?
The first step in the formation of a stomach ulcer is generally inflammation of the stomach lining, or gastritis. Most cases of gastritis are caused by the presence of H. pylori, but some are produced by the ingestion of NSAIDs (nonsteroidal anti-inflammatory drugs). Aspirin and ibuprofen are examples of NSAIDs.
Helicobacter produces chemicals that irritate and inflame the stomach lining. Researchers think that gastritis is mainly caused by the inflammatory response of the immune system as it attempts to fight the bacterial infection, however.
When gastritis is severe, the mucus lining the cavity of the stomach may be lost in one or more areas. This allows gastric juice to reach the cells of the stomach lining and damage them. The result is a sore called an ulcer.
In the vast majority of people, stomach acid doesn't cause peptic ulcers, though it may increase pain. There is one exception. People with a rare condition known as Zollinger-Ellison syndrome produce a hugely increased amount of stomach acid that often causes peptic ulcers.
Historical Determination of the Cause of Peptic Ulcers
Scientists have discovered that 80% of stomach ulcers and 90% of duodenal ulcers are caused by Helicobacter pylori. It wasn’t until 1982 that the bacterial cause of the ulcers was discovered. Before this time, ulcers were thought to arise due to stress and too much stomach acid.
Barry Marshall and Robin Warren, two Australian doctors, discovered that Helicobacter could cause ulcers. This idea that a bacterium could produce stomach ulcers was greeted by skepticism and even derision by other scientists. Barry Marshall drank a culture containing the bacterium to prove his theory. He developed a Helicobacter infection and gastritis as a result. Both doctors won a Nobel Prize for Medicine in 2005 for their discovery.
Helicobacter pylori - Diagnosis and Treatment
Many people have been found to have Helicobacter pylori infections without experiencing any discomfort, though they may still have low-grade gastritis. In fact, it’s estimated that at least 50% of the world’s population carries the bacterium within their bodies, with more people infected in certain countries than in others.
Scientists don’t know why some people develop symptoms from the bacterial infection and others don’t. They also don’t know how people become infected with Helicobacter, although they suspect that the bacterium may be obtained by eating and drinking materials contaminated by infected saliva or feces. Scientists recommend normal hygiene procedures to reduce the chance of a bacterial infection.
Different diseases often share symptoms. Someone who has any of the symptoms below and finds that they don't disappear within a short time period or that they recur should visit a doctor for a diagnosis.
Some Possible Symptoms of a Stomach Ulcer
The main symptom of a stomach ulcer is pain, but there may also be others. Symptoms may include:
- a dull, gnawing or burning pain in the stomach
- stomach pain that generally worsens after eating (while the pain of duodenal ulcers generally improves after eating)
- stomach pain that disappears temporarily after taking antacids
- heartburn (a burning sensation in the chest)
Untreated ulcers can lead to serious complications. The ulcers may bleed, which can cause anemia and fatigue. They may even become big enough to produce a hole in the stomach wall, allowing stomach contents to enter the abdominal cavity. The stomach contents can cause inflammation of the membrane lining the abdominal cavity and covering the organs. This potentially very dangerous condition is known as peritonitis. Another potential problem is that ulcers may partially or completely block the duodenal opening.
Peptic Ulcer Disease
It’s very important to treat stomach ulcers and gastritis caused by H. pylori. This is not only because of the complications that the bacterium may produce but also because a long-term infection increases the risk of stomach cancer.
Common Treatments for a Stomach Ulcer
Antibiotics prescribed by a doctor are likely to be the first line of attack for treating a stomach ulcer. They generally take two to three weeks to work. The doctor may also prescribe drugs to reduce the amount of acid that the stomach makes, since the acid irritates ulcers. The two main types of acid suppressors are H2 blockers and proton pump inhibitors.
Histamine is a chemical that stimulates the release of acid from cells in the stomach lining. The histamine must bind to receptors on the stomach cells in order to do its job. H2 blockers bind to the histamine receptors, stopping histamine from working.
Proton Pump Inhibitors
Proton pump inhibitors stop the process in which acid is transported from the acid-producing cells in the stomach lining into the stomach cavity. They are the preferred acid suppressor for stomach ulcers today.
Bismuth subsalicylate coats ulcers and helps block them from stomach acid. It also seems to help kill Helicobacter, but it can’t replace antibiotics. Bismuth subsalicylate (such as Pepto-Bismol and other brands) can be bought in drug stores. If your doctor is giving you medication for stomach ulcers and you want to add bismuth subsalicylate to the treatment you should let your doctor know.
A doctor should always be consulted when dealing with a peptic ulcer. The doctor's advice should be sought with respect to both medical and home treatments.
Medications are needed to heal a stomach ulcer, but other treatments may help to relieve pain. Eating frequent and smaller meals instead of less frequent and larger meals may be helpful. Small meals reduce the amount of acid that the stomach makes. Avoiding eating close to bedtime may also be helpful, since the food will stimulate acid production during the night. Using a different pain reliever instead of NSAIDs may also be beneficial.
Other lifestyle changes may also help to relieve ulcer pain. Quitting smoking and limiting or avoiding alcohol consumption are important strategies to try. Nicotine and alcohol irritate the stomach lining and may slow the healing of an ulcer. Emotional stress doesn’t cause ulcers but may increase the pain of an existing ulcer.
Diet and Pain
A bland diet used to be recommended for relieving ulcer pain. The diet contained soft foods like mashed potatoes and cream of wheat. It was also low in fat, non-acidic and contained no spices. Milk was said to help relieve pain.
Today most doctors say that a bland diet is unnecessary and that a person suffering from a peptic ulcer should eat healthy and nutritious food like everyone else. In addition, the idea that milk helps ulcers has been discounted. It may temporarily relieve pain, but the pain soon returns. Eliminating coffee consumption (caffeinated or decaffeinated) is said to reduce pain by some people, but many researchers say that there is no evidence that this strategy is effective.
A patient should avoid ingesting certain foods only if they have found that the foods increase their ulcer pain. Personal experience should determine which foods - if any - should be temporarily eliminated from their diet.
The Need for Further Research
Researchers are trying to learn more about how Helicobacter pylori affects the body, how it's transmitted and how it can be eradicated. There are still a lot of unanswered questions about the bacterium. As we discover more about its behaviour and about the body’s reaction to the infection, we will hopefully develop better ways to deal with Helicobacter.
References and Further Reading
© 2010 Linda Crampton
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