H. pylori infection

Definition

H. pylori infection occurs when a bacterium called Helicobacter pylori (H. pylori) thrives in your stomach or the first part of your small intestine.

H. pylori infection may be present in about half the people in the world. In industrialized countries the infection rate is about 20 percent to 30 percent, but in developing countries the infection rate may exceed 70 percent. However, most people who carry the bacteria experience no signs or symptoms of infection.

H. pylori infection is the most common cause of stomach ulcers, and it also causes inflammation of the stomach lining. H. pylori infection may also contribute to stomach cancers and other digestive system cancers.

Antibiotics used to eradicate H. pylori bacteria are usually part of a multiple-drug strategy to treat disorders caused or worsened by H. pylori infection.

Symptoms

The H. pylori bacterium produces toxins that may affect cells in the lining of your stomach or induce inflammation. Researchers are still investigating and characterizing exactly how these toxins work and how they lead to illnesses.

Although most cases of H. pylori infection produce no signs or symptoms, the toxic properties of the bacterium can lead to disorders of the stomach or the first part of your small intestine (duodenum). Signs and symptoms associated with H. pylori infection can vary in severity and duration depending on which disorder is present. If you have an H. pylori-related disease, you may experience the following signs and symptoms:

• An ache or burning pain in your abdomen
• A change in appetite with weight loss
• Nausea
• Vomiting
• Frequent burping
• Bloating
• Bloody vomit or vomit that looks like coffee grounds
• Bloody or black tarry stools

Disorders associated with H. pylori infection
It's not entirely clear why some people with H. pylori infection remain apparently healthy and some develop digestive system disorders. It's also unclear why some people exhibit milder disorders and others more severe disorders. Factors that may make a difference include varying degrees of virulence in different strains of H. pylori and genetic factors that may make some people more vulnerable to one of the following H. pylori-related disorders:

• Stomach and duodenal ulcers are open sores in the lining of your stomach or the first part of the small intestine (duodenum). H. pylori infection causes the majority of these ulcers. The most common sign of an ulcer is a frequent burning pain in your abdomen. The pain occurs most often when your stomach is empty and may last only a few minutes or several hours.
• Gastritis is inflammation of your stomach's lining. While signs and symptoms are often similar to those of ulcers, you may have gastritis with no apparent problems at first. H. pylori infection can cause a chronic inflammatory response that over time damages the lining of your stomach and results in the loss of acid-producing glands in your stomach. These changes can increase your risk of developing stomach cancer.
• Stomach cancer is a disease in which abnormal cells in your stomach divide without control. H. pylori infection is a strong risk factor for certain types of stomach cancer. Most signs and symptoms occur only after the cancer is fairly well advanced. Additional problems associated with cancer may include a bloated or full feeling after a very small meal, difficulty swallowing, breath odor, excessive gas or a general decline in health.
• Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is the development of a cancerous tumor from white blood cells (lymphocytes) in the lining of your stomach. H. pylori infection greatly increases your risk of gastric MALT lymphoma, and nearly all people with the disease are infected with this bacterium.
• Nonulcer dyspepsia is stomach pain or discomfort not caused by an ulcer or another identifiable disorder that would result in the pain. The relationship between H. pylori infection and nonulcer dyspepsia isn't clear.

A peptic ulcer is a sore on the lining of your stomach, small intestine or esophagus. A peptic ulcer in the stomach is called a gastric ulcer. A duodenal ulcer is a peptic ulcer that develops in the first part of the small intestine (duodenum). An esophageal ulcer occurs in the lower part of your esophagus.

Causes

H. pylori bacteria enter your body through your mouth and pass into your digestive system. The stomach is generally a very hostile environment for many bacteria. But the H. pylori bacterium is especially well-adapted for survival in the stomach. It produces an enzyme that, through a series of biochemical processes, creates a low-acid buffer zone for itself.

Many people contract H. pylori infection as a child, and the infection persists into adulthood, but adults also can contract H. pylori.

The bacteria seem to be transmitted from one person to another through contact with saliva. You could, for example, contract an H. pylori infection by sharing an eating utensil with an infected person.

It could also be contracted from contact with fecal matter that harbors H. pylori. This can result from generally poor sanitary conditions or from poor hand-washing habits.

These types of transmission occur most often in circumstances with crowded living arrangements, inadequate sewage removal, poor personal hygiene or a lack of clean water.

When to seek medical advice

Although H. pylori infection can cause disorders that vary markedly in severity, the signs and symptoms among the disorders may be similar. If you experience any of the signs or symptoms, consult your doctor.

If you have any severe signs and symptoms, see your doctor immediately. These include:

• Sudden, severe, persistent abdominal pain
• Bloody vomit or vomit that looks like coffee grounds
• Bloody or black tarry stools
• Difficulty swallowing
• Full or bloated feeling after a small meal

Tests and diagnosis

Screening for H. pylori infection is part of a complete diagnostic work-up to determine the cause of stomach pain and related digestive system problems that you describe to your doctor.

Noninvasive tests
Because the vast majority of stomach and duodenal ulcers, as well as most cases of gastritis, are caused by H. pylori, several treatment guidelines recommend a test-and-treat approach. With this approach your doctor will use a noninvasive test to determine whether you have an H. pylori infection. If a test result is positive, you'll begin an antibiotic-based multiple-drug therapy to eradicate the bacteria.

After you've completed the prescribed course of treatment, your doctor may use one of the noninvasive diagnostic tests to determine if it worked, especially if you still have persistent symptoms. Additional diagnostic tests aren't performed if the treatment effectively rids your body of H. pylori and alleviates symptoms.

The noninvasive diagnostic tests recommended by the American Gastroenterological Association include:

• Breath test. This test takes advantage of H. pylori's acid-reducing properties. One step in this process is the breakdown of a naturally occurring chemical called urea.

  The breath test begins with drinking a solution containing urea molecules "tagged" with radioactive carbon. If you have an H. pylori infection, the carbon is released when the urea is broken down. The tagged carbon is absorbed into your body and expelled, as is other carbon waste, when you exhale. The process takes about 30 minutes. A special device can detect the tagged carbon in a sealed bag into which you exhale.

• Stool antigen test. This laboratory test can detect in your stool sample foreign proteins (antigens) associated with H. pylori infection.

Invasive tests
The simple test-and-treat approach isn't recommended if you're older than 55 (when stomach cancer is more prevalent), there's a history of stomach cancer in your family or any one of the following signs is present:

• Sudden, severe, persistent abdominal pain
• Significant weight loss
• Recurrent vomiting
• Bloody vomit or vomit that looks like coffee grounds
• Bloody or black tarry stools
• Difficulty swallowing
• Full or bloated feeling after a small meal
• Mass in your abdomen that your doctor can feel

If any of these factors exist or if the initial test-and-treat approach didn't eradicate H. pylori or alleviate symptoms, your doctor will order additional tests. These may include:

• Endoscopy. With this procedure a specialist threads a long flexible tube equipped with a tiny camera (endoscope) down your throat and esophagus and into your stomach and duodenum. Using this instrument, your doctor can view any irregularities in your upper digestive tract and remove tiny tissues samples. These samples can be sent out for laboratory tests to detect H. pylori infection.

  Endoscopy is the preferred diagnostic procedure because it is more sensitive for detecting complications of H. pylori and it allows for direct visualization and tissue sampling.

• Stomach X-ray, or barium upper gastrointestinal (GI) series.This test uses a series of X-rays to examine your esophagus, stomach and duodenum. Before the test, you'll drink a thick liquid (barium) that temporarily coats the lining of your stomach so that it shows up clearly on an X-ray. You may also take a gas-producing liquid or pill that stretches the stomach and separates its folds, thereby providing a better view of the lining. This test isn't as sensitive as endoscopy.

Treatments and drugs

Treatment for H. pylori infection is always part of a multiple-treatment strategy to treat the disorder caused by the infection.

Antibiotics
Your doctor will most likely prescribe a 14-day regimen of two antibiotics to eradicate H. pylori bacteria. Common combinations are:

• Clarithromycin (Biaxin) and amoxicillin (Amoxil, Trimox)
• Metronidazole (Flagyl) and amoxicillin (Amoxil, Trimox)
• Metronidazole (Flagyl) and tetracycline (Sumycin)

It's important to complete the full course of prescribed antibiotics as directed by your physician, even when you're feeling better. Failure to follow the treatment guidelines may not completely eradicate the infection and increases your risk of antibiotic-resistant strains of H. pylori.

Your doctor may use either a breath test or stool antigen test to determine whether the antibiotic treatment has eliminated the H. pylori infection.

While the antibiotic treatment can completely eradicate H. pylori bacteria, an infection can recur later.

Other treatments
If you're taking a double-antibiotic course for an ulcer or gastritis, your doctor will also prescribe one or more medications to alleviate symptoms and promote healing. The most commonly prescribed drugs include:

• Proton pump inhibitors. These prescription medications suppress acids by shutting down "pumps" in acid-producing cells. Examples include omeprazole (Prilosec), lansoprazole (Prevacid), rabeprazole (Aciphex) and esomeprazole (Nexium).

• Histamine-2 (H-2) blockers. These reduce the amount of hydrochloric acid released into your digestive tract. Available by prescription or over-the-counter (OTC), H-2 blockers include ranitidine (Zantac), famotidine (Pepcid), cimetidine (Tagamet) and nizatidine (Axid).
• Bismuth subsalicylate (Pepto-Bismol). This protects the lining of your stomach and duodenum.

If you're diagnosed with stomach cancer or gastric MALT lymphoma, your doctor may prescribe a double-antibiotic treatment in addition to the options you may have for treating the cancer, such as surgery, radiation therapy or chemotherapy. Eradication of the H. pylori infection may improve cancer treatment outcomes and help prevent the recurrence of cancer.

Prevention

The best prevention strategies for H. pylori infection are the same as the standard precautions against many infections:

• Wash your hands thoroughly. Use warm soapy water after using the toilet and before eating.
• Don't share dining utensils. Drinking glasses or eating utensils can act as a carrier to transmit bacteria from one person to another.
• Avoid contaminated food or water. Don't consume food or water that may have been contaminated by floodwater or sewage.