How a Common Stomach Bug Causes Cancer

Half the people in the world harbor this bacterium, but it sickens only a fraction. Why?

 Ulcers of the World, Unite

There are six and a half billion human stomachs on this little planet of ours, and over half of them are home to a microbe called Helicobacter pylori. Scientists have known about the bacteria since the late 1800s, but it wasn’t until the 1980s that Australian doctors noticed that H. pylori was in the stomachs of just about everyone with an ulcer. A swig of antibiotics turned out to be a great way to make ulcers disappear. Scientists have since demonstrated that H. pylori strikes up an uneasy truce with its human hosts. In most cases, H. pylori lives amicably in our stomachs. When the truce is broken, the microbe triggers a cascade of reactions that leave a stomach cratered.

Explainer: what is Helicobacter pylori?

In 1982, two Australians – Robin Warren and Barry Marshall – presented their first observations of strange bacteria living in the human stomach. They went on to propose that these bacteria caused a common condition called gastritis, which is essentially inflammation of the stomach. Around half the world’s population is infected with Helicobacter pylori, although this varies between countries and age groups, with the highest rate among the elderly. Around 15% of Australians are infected. Most infected people are blissfully unaware of their little passengers. But in around one in five infected people, the resulting gastritis can, many years later, lead to one of several diseases including peptic ulcers – open sores in the lining of the stomach. It was for discovering the link between Helicobacter pylori, gastritis and peptic ulcers that Marshall and Warren received the Nobel Prize in Physiology and Medicine in 2005.

Beyond the stomach: An updated view of Helicobacter pylori pathogenesis, diagnosis, and treatment

Helicobacter pylori (H. pylori) is an extremely common, yet underappreciated, pathogen that is able to alter host physiology and subvert the host immune response, allowing it to persist for the life of the host. H. pylori is the primary cause of peptic ulcers and gastric cancer. Optimal treatment for Helicobacter pylori has yet to be defined for all patients. Furthermore, rates of antibiotic resistance vary by region, and local resistance data should be used to guide treatment where available.

Do you have a gastrointestinal infection?

Gastrointestinal infections are more common than you think. People often develop them as a result of food that has been contaminated. One of the most common gastrointestinal infections is known as H. pylori (Helicobacter pylori). It is a common type of bacterial infection that occurs in the stomach and upper intestines.

Germs Are Us

Helicobacter pylori may be the most successful pathogen in human history. While not as deadly as the bacteria that cause tuberculosis, cholera, and the plague, it infects more people than all the others combined. H. pylori, which migrated out of Africa along with our ancestors, has been intertwined with our species for at least two hundred thousand years.

Helicobacter Pylori and Alzheimer's

The common bacteria, Helicobacter pylori (H. pylori), has recently come into focus as a contributing factor in a variety of human health problems. For example, the physician and scientist Dr. Barry Marshall shared the Nobel Prize for medicine with his colleague Dr. Robin Warren in 2005 for establishing the fact that most cases of stomach ulcers were not caused by stress and worry, as had long been supposed, but rather were due to infection of the stomach lining by H. pylori.

Helicobacter Pylori, Ulcer-Causing Bacteria, May Protect Against Diarrhea: Study

People who harbor ulcer-causing bacteria in their stomachs may be protected against some diarrheal diseases, according to an Israeli study.

Stress Doesn’t Cause Ulcers! Or, How To Win a Nobel Prize in One Easy Lesson: Barry Marshall on Being … Right

Marshall, along with his colleague and fellow Nobel winner Robin Warren, proved that up to 90 percent of peptic ulcers are caused by a bacterium called Helicobacter pylori — not by stress, as medical wisdom had long held. In most of the interviews in this series,

H. pylori – the silent (and sometimes deadly) bacteria inside us

H. pylori is also the only type of bacteria classified as a carcinogen because, if left untreated, it can progress to stomach cancer. Other complications include Barrett’s Oesophagus, a precursor to oesophageal cancer.

Scientist who braved ulcer wins Nobel

An Australian microbiologist who swallowed mouthfuls of bacteria to prove they cause stomach ulcers was awarded the 2005 Nobel prize in physiology or medicine for his pioneering research yesterday. Barry Marshall, who runs a laboratory at the University of Western Australia, received the award jointly with Robin Warren, formerly a pathologist at the Royal Perth hospital. The pair will share the 10m Swedish kronor (£730,000) prize money.

Why do we still have Helicobacter Pylori in our Stomachs

The existence of any infectious agent in a highly acidic human stomach is contentious, but the chance finding of Helicobacter pylori is by no means an accident. Once H. pylori colonises the gastric mucosa, it can persist for a lifetime, and it is intriguing why our immune system is able to tolerate its existence. Some conditions favour the persistence of H. pylori in the stomach, but other conditions oppose the colonisation of this bacterium.

Early Humans Left Trails of Ulcers

Helicobacter pylori are exquisitely adapted to live inside our stomachs (about half the world's people are infected, though 80 percent never show symptoms). Since the bacteria don't live outside our bodies, that means two things: first, they go where we go, and second, they evolve as we evolve. That's pretty useful if you're studying ancient human migrations, because people today are still carrying around H. pylori strains descended from the bacteria of their ancestors.

Great Moments In Medical Self-Experimentation

In 1984, Dr. Barry Marshall hypothesized that stomach ulcers were not caused by stress or by spicy foods (then conventional medical wisdom). Rather, he suspected they were caused by bacterial infection, based on biopsy data from patients as well as research with mice. However, most mainstream gastroenterologists thought he was crazy, and he was forbidden from testing his hypothesis on human subjects. However, Dr. Marshall could test his theory on himself.

H. pylori at last gets its due

Nevertheless, although the two physicians, Dr. Barry Marshall and Dr. Robin Warren, first identified h. pylori as the "ulcer bug" 23 years ago, most people still think of ulcers as the product of stress. Even the medical community took nearly a decade to give h. pylori its due - clinicians continued into the mid-1990s to prescribe antacids instead of antibiotics as ulcer treatments. (The thought was that stress led the body to produce too much stomach acid, which ate through the stomach's lining.)

Helicobacter Pylori- The Silent Epidemic

Not all H. pylori infections lead to the development of ulcers and stomach cancer. However, most people infected do develop gastritis. Unless eradicated, H. pylori will remain in the stomach and will continue to cause chronic inflammation and weakening the protective force of the mucous membrane of the stomach. This will result in creating a condition whereby it is vulnerable to attack by stress, salty meals and carcinogenic substances.

I Eat at Restaurants for a Living. That’s Not Why My Stomach Always Hurt

Half the world’s population has H. pylori, a type of bacteria that can mess with digestion. So why doesn’t the problem have a higher public profile?

The twists and turns of fate

Helicobacter pylori has a reputation for causing ulcers and cancer. Hunting it to extinction, however, may be a mistake. MOST people feel a twinge of regret at reports that an animal or plant is becoming rare. Should they feel the same pangs for a bacterium? With Helicobacter pylori, so-called because of its twisty-turny shape, and famous for causing stomach ulcers and gastric cancer, the reaction would probably be “good riddance”. And H. pylori is, indeed, endangered in many parts of the planet. It is fast vanishing from the rich world, thanks to antibiotics and improved hygiene. Yet, as conservationists of larger organisms are quick to remind you, extinctions can have unexpected consequences. And that may prove to be the case with H. pylori.

To Solve a Medical Mystery, This Doctor Drank Live Bacteria

Dr. Barry Marshall swallowed helicobacter pylori to prove it was the cause of a common ailment.