The Helicobacter genus represents a group of spiral-shaped bacteria that inhabit the acidic environment of the stomach. Their helical form is believed to help them move through the stomach’s thick mucous lining. While many individuals carry these microorganisms without adverse effects, their presence is a factor in certain health outcomes, making them a focus of medical research.
The Helicobacter Family
The most recognized species is Helicobacter pylori. It is a gram-negative bacterium measuring 2.5 to 5 micrometers in length. H. pylori is responsible for the majority of health conditions linked to this genus, and its discovery revolutionized the understanding of stomach-related ailments.
Beyond this well-known species, the genus includes numerous non-pylori Helicobacter species (NHPH), which are less commonly found in humans. There are at least 42 identified species of Helicobacter. Species such as H. suis (from pigs), H. felis (from cats), and H. bizzozeronii (from dogs) primarily colonize animals but can, on occasion, be transmitted to humans, a process known as zoonosis.
While infections with these other Helicobacter species are considerably rarer than H. pylori infections, they can lead to similar gastric symptoms like inflammation of the stomach lining. The overall impact of these other species on human public health remains limited compared to H. pylori.
Transmission and Colonization
The transmission routes of Helicobacter are not definitively established, but evidence points toward person-to-person spread through oral-oral or fecal-oral contact. These modes of transmission are more common in crowded living situations and areas with inadequate sanitation. Contaminated food and water are also considered potential sources of infection.
Once inside the body, Helicobacter bacteria must survive the acidic environment of the stomach. They achieve this by producing an enzyme called urease, which neutralizes stomach acid in the bacterium’s immediate vicinity. This allows the spiral-shaped bacteria to use their flagella, which are whip-like appendages, for motility. They burrow into the protective mucus layer and adhere to the surface of the gastric epithelial cells, shielded from digestive fluids.
Associated Health Conditions
The most common outcome of a persistent Helicobacter infection is chronic gastritis, an inflammation of the stomach lining that often develops without noticeable symptoms. This prolonged inflammation can damage the stomach lining and lead to peptic ulcers. The bacteria cause these painful sores by disrupting the protective mucus layer and stimulating excess acid production. It is estimated that 10% to 20% of infected individuals will develop an ulcer in the stomach or small intestine.
In a smaller fraction of cases, a long-term infection can lead to more severe outcomes. The World Health Organization has classified H. pylori as a Class I carcinogen, as it is linked to cancer in humans. It is the leading cause of gastric adenocarcinoma and is also associated with a rare stomach cancer called gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Only about 1% to 3% of people with the infection will develop gastric cancer.
Diagnosis and Treatment Approaches
Identifying a Helicobacter infection can be accomplished through several methods. Non-invasive tests are commonly used first and include the urea breath test, where a patient drinks a special solution and their breath is analyzed. Another method is the stool antigen test, which detects bacterial proteins in a fecal sample. If further investigation is needed, an endoscopy can be performed to obtain a tissue sample, or biopsy, for direct testing.
The primary goal of treatment is the complete eradication of the bacteria from the stomach. Standard medical care involves a course of multiple medications taken together for about two weeks. This is often referred to as “triple therapy” or “quadruple therapy” and includes a combination of at least two different antibiotics to prevent resistance.
Alongside the antibiotics, a medication that reduces stomach acid, known as a proton pump inhibitor (PPI), is prescribed. The PPI helps alleviate symptoms and allows the inflamed stomach lining to heal more effectively. Completing the entire prescribed course of all medications is necessary to ensure the infection is fully cleared and reduce the chance of it returning.