Helicobacter pylori, commonly called H. pylori, is a type of bacteria that infects the stomach and small bowel. It was discovered in 1982 by two Australian researchers who also found that it causes peptic ulcer disease.

Peptic ulcers are open sores in the lining of the stomach or the upper part of the small intestine. Peptic ulcers are often simply called “ulcers” or “stomach ulcers.” H. pylori also increase the risk of developing stomach cancer and gastritis.

This article explains what H. pylori are, how it makes people sick, and how it causes stomach ulcers.

Many people with H. pylori do not have any signs or symptoms. However, if people get an illness caused by H. pylori, they may have various symptoms.

Symptoms of a stomach ulcer might include a dull or burning pain in the upper belly area. The pain is sometimes worse at night or when the stomach is empty. There may be temporary relief from taking an antacid. However, the pain does come back.

Symptoms of gastritis often include upper belly pain, nausea, and vomiting.

Possible symptoms of stomach cancer include:

  • belly pain or swelling
  • loss of appetite
  • nausea or indigestion
  • feeling full without eating very much
  • vomiting

People with any of these symptoms should talk with their doctor. Other conditions can cause these symptoms, so proper medical care is needed to diagnose the issue.

Possible complications of stomach ulcers

An ulcer can lead to serious complications if left untreated, including:

  • internal bleeding that can become life-threatening
  • a hole in the stomach that can lead to infection
  • scar tissue that can block the stomach or intestine, preventing it from emptying food

These complications require immediate medical attention. Possible warning signs include:

  • severe stomach pain
  • black or tarry stool
  • stool with bright red blood
  • vomit with bright red blood
  • vomit that resembles coffee grounds
  • feeling weak or short of breath
  • feeling dizzy or faint
  • chills or fever

The stomach has a layer of mucus designed to protect it from stomach acid. H. pylori attack this mucus lining and leave part of the stomach exposed to acid. Together, the bacteria and the acid can irritate the stomach, causing ulcers, gastritis, and in rare cases, stomach cancer.

Many people who have H. pylori in their stomachs do not develop ulcers or any other related problems. In fact, two-thirds of the world’s population have H. pylori, according to the Centers for Disease Control and Prevention (CDC).

In the United States, there is a 5% prevalence of the bacteria in children less than 10 years old. Hispanic and African American populations have a higher prevalence compared with white Americans. About 60% of Hispanics and 54% of African Americans have H. pylori compared to 20–29% of white Americans.

However, for reasons not yet understood, some people get ulcers, gastritis, or stomach cancer from an H. pylori infection.

Research has shown that in the first 10 years since scientists discovered H. pylori, Data from the developed world has shown that in the first decade of the discovery of H. pylori, 95% of duodenal ulcers and 85% of gastric ulcers were associated with this bacterial infection.

Furthermore, the lifetime risk of developing peptic ulcer disease (PUD) maybe 3–10 times higher in people who test positive for H. pylori than those who do not.

Ulcers are not the only problems associated with H. pylori. Researchers discovered that H. pylori may also cause gastritis, a condition that involves inflammation of the stomach’s lining.

H. pylori infection is also linked to stomach cancer. However, the American Cancer Society states that most people with H. pylori in their stomach never develop stomach cancer.

It is worth noting that peptic ulcers may also occur due to the long-term use of certain medications, including pain medications such as ibuprofen, aspirin, and naproxen. These medications are called non-steroidal anti-inflammatory drugs (NSAIDs).

Doctors can conduct a blood test to see if H. pylori antibodies are present in a person’s blood. However, since antibodies can remain in the body after the bacteria is gone, this may not be the best way to test for an active infection.

Other ways to test for the bacteria include:

  • An urea breath test (UBT), in whuch a person swallows a capsule containing urea and then gives a breath sample after 10–20 minutes. This allows the doctor to see if the bacteria is present in the stomach.
  • An endoscopy can help a doctor find the infection, as well as any related ulcers or inflammation.
  • A stool sample can also show if a person has antigens for the bacteria on their stoll. This tells the doctor if the person has an active infection.

Doctors diagnose ulcers, gastritis, and stomach cancer with a combination of the following tests:

  • Medical history: Past medical problems and symptoms are discussed.
  • Physical exam: The doctor will examine and listen to the belly.
  • Special X-rays: These can show the inside of the stomach.
  • Endoscopy: Doctors view the inside of the stomach with a special instrument while the patient is sedated or put to sleep.

H. pylori is contagious, though the way it transmits is not clear. The two most likely ways the bacteria transmit are:

  • direct person-to-person transmission
  • environmental contamination

When it comes to environmental contamination, the likely source is contaminated food or water. It has been found in human saliva, so experts think it can spread from person to person.

There is no known way to prevent H. pylori infection. However, experts recommend:

  • Washing hands before eating and after using the restroom.
  • Eating food that has been handled and prepared safely.
  • Drinking only clean, safe drinking water.

H. pylori infections are more common in developing countries where people may not have access to clean, safe food and water.

People who have symptoms of an ulcer, gastritis, or another stomach issue may receive testing for H. pylori or other problems. If doctors find an ulcer, they may treat patients with a variety of medications, including some or all of the following:

  • antibiotics to kill H. pylori
  • medications that reduce stomach acid called proton pump inhibitors (PPIs) or histamine receptor blockers
  • medications that coat the ulcer and help it heal

Sometimes, a peptic ulcer can come back after treatment. To help avoid this, experts recommend that a person:

  • Stop NSAIDs or take a much smaller dose.
  • Only take NSAIDs with special medications that protect the stomach.
  • Avoid alcohol.
  • Consider quitting smoking.

Experts also recommend that children and adolescents with H. pylori are first treated simultaneously with 1-2 mg/kg/day of a proton pump inhibitor (PPI), and two different antibiotics: amoxicillin (50 mg/kg/day) and clarithromycin (20 mg/kg/day).

This treatment should last 14 days. If this is not successful, the doctor may attempt to increase the dosages or substitute the antibiotics.

Doctors can treat most H. pylori infections successfully treated with antibiotics.

However, research suggests that some H. pylori infections are becoming resistant to certain antibiotics. This means H. pylori is able to survive antibiotic treatment, and the patient may need another drug to kill the bacteria.

A 2015 review found some patients in the United States had H. pylori infections that were resistant to two different antibiotics. A 2014 review found a high number of resistant H. pylori bacteria in Latin American countries.

Antibiotic resistance is a growing problem across the globe. The CDC says that more than 35,000 people die each year as a result of an antibiotic-resistant infection.

Many people may have heard of methicillin-resistant (Staphylococcus aureus (MRSA). However, there are many other types of bacteria that have become resistant to antibiotics.

Everyone can do their part to help fight the problem of antibiotic resistance. The CDC says that people should:

  • Use antibiotics only when prescribed by a doctor.
  • Never use antibiotics for colds or the flu — these are viruses and antibiotics will not work against these illnesses.
  • Take the entire course of antibiotics if they have been prescribed.
  • Never share antibiotics with others.
  • Never use old or leftover antibiotics.

Fortunately, H. pylori are still treatable with several different antibiotics. Quick treatment will help prevent damage to the stomach and the possible problems of ulcers, gastritis, and stomach cancer.