Helicobacter pylori (H. pylori) is a gram-negative, microaerophilic bacterium found in the stomach. It is known for its role in causing gastric ulcers and chronic gastritis, conditions that are precursors to stomach cancer. It is uniquely adapted to survive in the harsh acidic environment of the stomach.

The name defines the form and location of this bacterium:

• Helicobacter refers to the helical shape of the bacterium. This spiral shape helps it to penetrate the stomach mucosa and attach itself to the underlying epithelial cells.
• Pylori refers to the pylorus, the area of the stomach where this bacterium is often found.

It is equipped with flagella, whip-like appendages that enable it to move.

It produces an enzyme called urease, which neutralises stomach acid by converting urea to ammonia and carbon dioxide, creating a more hospitable environment for the bacterium, which has a unique way of evading the body's immune response, allowing it to persist in the stomach for long periods, often for the host's lifetime if left untreated.

It is typically acquired during childhood and can be transmitted from person to person through saliva, faecal contamination or poor hygiene practices.

Treatment usually involves a combination of antibiotics and proton pump inhibitors to reduce stomach acid and allow the antibiotics to act more effectively.

Studies

Matsuo Y, Kido Y, Yamaoka Y. Helicobacter pylori Outer Membrane Protein-Related Pathogenesis. Toxins (Basel). 2017 Mar 11;9(3):101. doi: 10.3390/toxins9030101. 

Abstract. Helicobacter pylori colonizes the human stomach and induces inflammation, and in some cases persistent infection can result in gastric cancer. Attachment to the gastric mucosa is the first step in establishing bacterial colonization, and outer membrane proteins (OMPs) play a pivotal role in binding to human cells. Some OMP interaction molecules are known in H. pylori, and their associated host cell responses have been gradually clarified. Many studies have demonstrated that OMPs are essential to CagA translocation into gastric cells via the Type IV secretion system of H. pylori. This review summarizes the mechanisms through which H. pylori utilizes OMPs to colonize the human stomach and how OMPs cooperate with the Type IV secretion system.

Gu H. Role of Flagella in the Pathogenesis of Helicobacter pylori. Curr Microbiol. 2017 Jul;74(7):863-869. doi: 10.1007/s00284-017-1256-4. 

Abstract. This review aimed to investigate the role of Helicobacter pylori flagella on the pathogenicity of this bacterium in humans. Helicobacter pylori is a flagellated pathogen that colonizes the human gastroduodenal mucosa and produces inflammation, and is responsible for gastrointestinal disease. Its pathogenesis is attributed to colonization and virulence factors. The primary function of H. pylori flagella is to provide motility. We believe that H. pylori flagella play an important role in the colonization of the gastrointestinal mucosa. Therefore, we reviewed previous studies on flagellar morphology and motility in order to explore the relationship between H. pylori flagella and pathogenicity. Further investigation is required to confirm the association between flagella and pathogenicity in H. pylori.

Sabbagh P, Javanian M, Koppolu V, Vasigala VR, Ebrahimpour S. Helicobacter pylori infection in children: an overview of diagnostic methods. Eur J Clin Microbiol Infect Dis. 2019 Jun;38(6):1035-1045. doi: 10.1007/s10096-019-03502-5. 

Abstract. Children differ from adults regarding Helicobacter pylori (H. pylori) infection in many terms. H. pylori infection represents a key factor in the pathogenesis of duodenal ulcer and chronic gastritis in children. H. pylori infection causes some extraintestinal diseases as well as gastrointestinal diseases. Although, among these illnesses in children, symptoms like recurrent abdominal pain are not specific. Moreover, the role of the pathogen in the growth faltering, iron deficiency anemia, and asthma still remains controversial. A reliable method to detect H. pylori infection is a crucial issue, sand is still a matter of active debate. The tests applied for H. pylori diagnosis are grouped as either invasive or non-invasive methods. Invasive methods consist of endoscopic evaluation, the rapid urease test (RUT), histology, and bacterial culture. Non-invasive tests include the urea breath test (UBT), stool antigen test (SAT), serology, and molecular diagnostic approaches. Use of endoscopy is a pre-requisite for all invasive methods and poses difficulties in children as it is a difficult procedure and requires patient's cooperation. For this reason, the non-invasive tests have been commonly used in children, although their accuracy is not very reliable in some cases. Invasive tests may be opted to confirm the diagnosis as and when needed. This review presents the diagnostic tests used to detect H. pylori infection in children.