What is Helicobacter pylori infection

Helicobacter pylori (H. pylori or Helicobacter p.) Is a gram-negative bacterium that, unlike most other bacteria, is able to colonize the acidic environment of the human stomach.

Helicobacter pylori infection is the most common cause of permanent inflammation of the stomach lining and is held responsible for various other diseases of the stomach and esophagus. But in addition to causing illness, the bacterium can also have some positive effects in the body.

Robin Warren and Barry Marshall received the 2005 Nobel Prize in Physiology for their discovery of the Helicobacter pylori bacterium and its role in the development of chronic gastric inflammation.


Worldwide, Helicobacter pylori bacteria can be found in the gastrointestinal tract in around half of the world's population over 40 years of age. However, only about 10-15% of those affected develop the known symptoms.

The number of those affected differs significantly in the industrialized and developing countries. In England, for example, around 13% of the population is affected, while in Korea 81% carry the germ.

There is a clear age-dependent increase in the number of infected people - around 1% per year of life in industrialized countries. In Germany, around 3% of children aged 4 and over and around 48% of adults are affected (<30 years = approx. 22% and> 65 years approx. 80%).

However, the number of Helicobacter p. Infections in Germany and other industrial nations is decreasing from year to year.

Helicobacter pylori infection can be detected in about 75% of people who have a gastric ulcer and about 99% of those who have been diagnosed with duodenal ulcer.

How the germ is passed on is not yet entirely clear. But it seems that the transmission takes place from person to person and mostly through close family contact from mother to child.

How can Helicobacter pylori survive in the stomach?

Stomach acid with its pH between 1 and 1.5 is a very strong acid. Such an acidic environment is deadly (bactericidal) for most bacteria.

The H. pylori bacterium produces an enzyme that can neutralize acids. In its environment - on the stomach wall - it creates an acid-free area in which it can survive protected.

Our immune system reacts to the colonization of the stomach with Helicobacter pylori, but it cannot fight the bacteria effectively. The constant activity of the immune system is blamed for various diseases of the stomach and esophagus.

Symptoms of Helicobacter pylori infection

Due to the constant immune reaction to the bacterium in the stomach, symptoms such as:

  • Bloating
  • nausea
  • Loss of appetite
  • Bad breath
  • Eructation
  • Pain in the upper abdomen

But often people with Helicobacter p. is proven, no complaints at all.

Possible diseases as a result of Helicobacter pylori infection

The following diseases can be triggered by the constant immune reaction to the bacterium:

  • Acute and chronic inflammation of the stomach lining (gastritis),
    which is known as type B gastritis (B for bacterial). Often the gastric mucosal inflammation is acute after infection with the bacterium. However, it can also develop into a chronic inflammation of the gastric mucosa.
  • Gastrointestinal tumors
    Long-term colonization can lead to inflammations such as duodenal ulcers, gastric ulcers, duodenal ulcers, but also gastric carcinomas and so-called MALT lymphomas in the gastrointestinal area. It is believed that the risk of developing gastric cancer increases by 20 to 40% with Helicobacter pylori gastritis.

The positive effects of infection on the immune system

An early infection of the stomach with Helicobacter pylori can change the composition of the intestinal flora as well as the immune defense of the lungs and influence the hormonal balance.

  • Less common asthma and allergies
    In 2011, scientists from the University of Zurich and Johannes Gutenberg University Mainz demonstrated in animal experiments that mice that were a few days old and infected with Helicobacter pylori developed an immunological tolerance to the bacterium and consequently did not react or only slightly reacted to strong asthma-causing allergens .
    In 2016 a team of scientists from Graz and New York researched the complex interaction of Helicobacter, microbiome and immune system in humans and found that the Helicobacter bacterium stimulates, among other things, the production of the hormone ghrelin, which not only increases appetite, but also influences the immune system , so that those affected are better protected against allergies and asthma.
    The American microbiologist Martin Blaser of NYU Langone Medical Center in New York found that children who were infected with an aggressive variant of H. pylori before the age of 15 were 40 percent less likely to develop asthma. He suspects that the incidence of allergic diseases is increasing due to the decreasing H. pylori infection rate in industrialized nations.
    Other studies suggest a protective effect against diseases of the esophagus or the intestines.
  • Gut flora changes
    A research team was surprised that the Helicobacter p. Infection leads to changes in the composition of the intestinal flora, which also protect the intestines and the esophagus. Martin Blaser from New York found that people without Helicobacter are more likely to have inflammation of the esophagus or reflux disease and that they are more likely to develop esophageal cancer. [DLF: Helicobacter: a villain who also does good]
    Thanks to the increasing disappearance of the bacterium, according to Blasius, fewer people die from stomach cancer, but more suffer from heartburn and esophageal cancer. [Martin J. Blaser: "Antibiotics overkill - This is how modern epidemics arise", Herder Verlag, Freiburg im Breisgau 2017,]
  • Accumulation of T cells in the lungs
    Further research found that Helicobacter pylori infection leads to the build-up of certain T cells, a group of white blood cells used for immune defense, in the lungs.


An infection with the H. pylori bacterium can be diagnosed using various invasive and non-invasive methods. They differ in their accuracy, the effort required and the risks.

  • Invasive diagnostic procedures
    • Gastroscopy
    • Tissue examination (biopsy)
    • Bacterial cultures
  • Non-invasive diagnostic procedures
    • Blood tests
    • Saliva, urine and stool tests
    • Breath test

Invasive diagnostic methods for H. pylori infection

  • Gastroscopy
    With a gastroscopy, the doctor can detect inflammatory reactions in the stomach. In addition, the presence of gastric ulcers may indicate Helicobacter pylori infection.
  • Tissue examination (biopsy)
    During a gastroscopy, tissue samples can be taken from inflamed areas of the gastric mucosa, which are then examined under a microscope for the presence of Helicobacter pylori.
    In the so-called Helicobacter urease test (HUT or CLO test), a tissue sample is placed in a urea-containing color indicator solution. The Helicobacter bacteria convert the urea in this test medium into ammonia and carbon dioxide and color the indicator red. This test is also called the bedside test because the test result can be read after a few minutes up to a maximum of 24 hours.
    The Helicobacter urease test can be falsified by various drugs (including proton pump inhibitors (PPI) and antibiotics.
  • Bacterial cultures
    Bacteria can be grown in the laboratory from the tissue samples taken during gastroscopy and thus detected.

Non-invasive diagnostic methods for H. pylori infections

  • Blood tests
    Antibodies that the immune system has formed against the bacterium can be detected in the blood. Such a test can give an indication of the extent of the Helicobacter pylori infection. Antibodies in the blood cannot tell whether there is an acute infection or whether it occurred a long time ago.
  • Saliva, urine and stool tests
    Antibodies can also be detected in saliva, urine and stool samples. Here, too, the sole detection of antibodies is not reliable evidence of an acute infection.
  • Breath test
    The C13 breath test (13C urea breath test) uses the metabolism of the bacterium to detect Helicobacter pylori in the stomach. Before starting the test, the patient must be fasted for at least four hours. Then he drinks a fruit juice that contains labeled urea (13C-urea). If the patient is infected with Helicobacter pylori, the bacterium in the stomach converts the urea, among other things, into carbon dioxide (CO2), which is exhaled and, because it is marked, can be detected.

A diagnosis, according to the recommendation of many doctors, should only be initiated if a therapeutic consequence arises from it.

Therapy of infection with H. pylori

For most people, infection with Helicobacter p. Bacteria is harmless and does not require treatment.

However, if the Helicobacter p. Bacteria cause inflammation, the infection can be treated with a combination of different drugs.

The new S2K guideline Helicobacter pylori and gastroduodenal ulcer disease from 2016 [https://www.awmf.org/uploads/tx_szleitlinien/021-001l_S2k_Helicobacter-pylori-gastroduodenale_Ulkuskrankheit_2018-08.pdf] recommends the classic triple therapy and alternative therapy with quadruple therapy and quadruple therapy or without bismuth salt (also bismuth or bismuth).

What these therapies have in common is that they consist of a combination of antibiotics that kill bacteria and a drug that protects the stomach (proton pump inhibitors (PPIs)).

Therapy regimenMedication
Italian triple therapyProton Pump Inhibitor (PPI), Clarithromycin, Metronidazole
French triple therapyProton Pump Inhibitor (PPI), Clarithromycin, Amoxicillin
Quadruple Therapy
Combination therapy of a proton pump inhibitor and bismuth triple therapy
Proton Pump Inhibitor (PPI), bismuth salt, tetracycline, metronidazole
Combined quadruple therapyProton Pump Inhibitor (PPI), Clarithromycin, Amoxicillin, Metronidazole

Helicobacter pylori therapy is also known as eradication therapy and lasts 7 to 14 days. After this time has elapsed, another test is carried out for the presence of Helicobacter pylori in the gastrointestinal tract, for example using the 13C urea breath test.

Since Helicobacter pylori infection is a major risk factor for gastric carcinoma and other cancers of the esophagus, the guideline recommends risk patients, i.e. patients who have developed gastritis as a result of the infection, a guideline-compliant therapy as a cancer prophylaxis.


An infection with Helicobacter pylori can go unnoticed for a lifetime or for a long time, since consequences often only become noticeable after a while, if at all. For people who frequently suffer from gastrointestinal complaints, it is advisable to test for the presence of the bacteria and then treat them if they are infected with Helicobacter p. Bacteria. In this way, the symptoms of the infection can often be eliminated and long-term effects effectively prevented.


The S2k guideline Helicobacter pylori (updated 2016) states that there are no recognized prevention strategies to prevent H. pylori infection. An effective vaccination is currently not available.

Helicobacter pylori self-test

Various Helicobacter self-tests are now available that test the blood for Helicobacter pylori antibodies and can be used at home. They are considered 70-90% reliable. With the help of a lancet, blood is taken from the fingertip and placed in a test cassette. After adding a diluent, the test result can be read within 10 minutes (similar to a pregnancy test).

If an infection with Helicobacter pylori is suspected as the cause of gastroenterological complaints, a visit to the doctor is recommended.