Helicobacter Pylori: how it is made and how it resists in the stomach

The name of Helicobacter pylori recalls both itsshapeand the place where it preferably nests: thehuman pylorus, that is the final stretch of the stomach, point of passage with the intestine.

Helicobacter pylori is a unicellular organism smaller than human cells and equipped with flagella useful for moving in an aqueous environment. Compared to Gram positive, it has a cell wall that is more resistant to antibiotics.

The most important characteristic of this bacterium, however, is theability to survive in a strongly acidic environmentwith pH values of 1-2. It is considered anextremophile, that is, an organism capable of surviving in environments considered extreme for life.

The spiral shape, along with the flagella, allows it to nest in the mucous membrane of the stomach, and the acid resistance of not suffering damage due to hydrochloric acid of gastric juices.

Helicobacter pylori hasspecific channels for ureathat open, letting it in, when the pH is too low. It is also able to produce a particular protein, with an enzyme function, calledUrease. This protein hydrolyzes incoming urea producing ammonia and carbon dioxide (CO₂), which are then released outside. Ammonia, dissolved in an aqueous environment, gives a certain basicity to the solution that locally decreases the acidity of the stomach. In this way, a less acidic micro-environment is created around the bacterium in which it can survive as in a sort of bubble.

To start this chemical reaction, however, it requires Urea, normally present in the human stomach, without which it loses the ability to resist. This strong specialization to live in the stomach, however, means thatit is not able to survive in an acidic environment free of urea.

In addition to what has already been said, in order to make its way into the mucosa, Helicobacter pylori produces a series ofcytotoxinsandmucolytic enzymesharmful to the cells of the human stomach. All this causes inflammationin a first phase and thenulcers. Ulcers, prolonged (and then chronic) inflammatory state are a source of risk for stomach cancer.

Who does it hit?

According to data reported by the CDC (Centers for Disease Control), about two-thirds of the world’s population is infected with H. pylori

As indicated by international data verified by the Health Institute , in industrialized countries the infection affects 20% of the population under 40 years of age, to reach 50% of the population over 60 years of age.

The most common symptoms of Helicobacter pylori infection

The infection is often asymptomatic. In cases where the infection presents itself with symptoms, we can include among them:

• disorders coinciding with those of a normal gastritis and ulcer
• Backflow
• nausea
• Slow digestion
• He retched
• sense of heaviness

In all cases it is difficult to associate such non-specific symptoms with this particular infection.
For this reason, diagnostic tests are performed when a Helicobacter pylori infection is suspected.

Does Helicobacter pylori cause cancer?

Chronic Helicobacter pylori infection has been shown to infection increase the risk of developing stomach cancer by 2-6 times .

Helicobacter pylori produces a toxin (CagA) which causes inflammation of the cells of the stomach wall. The inflammatory state can favor genetic mutations which in turn can cause cancer.

Helicobacter infection has also been associated with the development of Pancreatic Cancer ( ) and that of  GastricMALT lymphoma ( Source ).

As always, it should be remembered that it is a risk factor and the presence of the bacterium does not imply that cancer is certain, but more and more genetic and environmental factors are involved which cooperate for the development of a tumour.

On the other hand, the ability of the bacterium to decrease the acidity of the stomach reduces the risk of cancer of the cardia and adenocarcinoma of the esophagus ( Source ).

Diagnostic tests for Helicobacter pylori: how do they work?

There are several tests to determine the presence of Helicobacter pylori infection, some invasive and some not.

One of the most common and least invasive is the Urea breath test,which exploits the chemical reaction catalysed by the bacterium’s urease to identify it.

This test involves taking a sample of the patient’s breath to use as a reference. Then a tablet of Urea labeled with Carbon 1313C), a heavy non-radioactive isotope of carbon, is administered. After waiting 30 minutes, a new breath sample is taken. The difference in the concentration of CO labeled in the two breath samples, if higher than a certain value, is proof of the presence of infection. In fact, labeled urea is hydrolysed producing CO with an excess ofC only if Helicobacter pylori is present.⁽₂₂¹³

The analysis of the air samples is carried out through mass spectrometry , a technique capable of distinguishing between “normal” carbon dioxide and the heavier one labeled with C.¹³

Another non-invasive test consists in the search for  antibodies against Helicobacter Pylori in the blood (serological analysis).

A third possibility is to verify the presence of Helicobacter Pylori antigens (fragments of the bacterium) in the faeces, analyzing them in the laboratory with the use of specific antibodies.

An invasive method consists, however, in the observation andbiopsy of small portions of the stomach wallthrough gastroscopy. In this way, the presence of the bacterium can be assessed with the rapid urease test. The method consists in placing the sample taken in a substrate containing Urea and a pH indicator. If the bacterium is present, the urea is hydrolysed and the ammonia produced modifies the pH and therefore the color of the indicator.

Treatment by Helicobacter pylori

The treatment consists in the administration of one or morespecific antibioticstogether with aninhibitor of the proton pumpa, ie the urea channel of the bacterium. This molecule causes the channel not to open. In this way Helicobacter pylori cannot let urea enter, cannot hydrolyze it and, without being able to counteract the external acidic environment, dies.