The doctor who drank bacteria to show what causes ulcers

For decades, stomach ulcers were blamed on stress and spicy food. Two doctors in Perth found a bacterium behind many of them, and one of them drank it to make the case.

For much of the twentieth century, a stomach ulcer had a familiar explanation: stress, spicy food and too much acid. There was also a firm belief about the stomach itself. Its acid was thought to be far too harsh for bacteria to live there.

In 1981, Barry Marshall, a young doctor training at Royal Perth Hospital in Australia, met Robin Warren, a pathologist there with an interest in gastritis, the inflammation of the stomach lining. Together they tried to grow a bacterium from stomach samples in the lab, and it kept failing. The first 30 samples showed nothing. The 31st was left longer than the usual two days, and colonies finally appeared. The organism simply grew more slowly than anyone had allowed for.

In 1982 they proposed that this bacterium, later named Helicobacter pylori, caused ulcers. The idea met strong resistance. In 1983 the Gastroenterological Society of Australia turned down their paper and ranked it among the bottom 10 percent of the year's submissions.

The experiment on himself

Attempts to infect piglets had failed. So in 1984, after an endoscopy showed his own stomach was healthy, Marshall drank a broth of the cultured bacteria. Within three days he had nausea and bad breath, and between days five and eight he was vomiting. On day eight, a second endoscopy found severe gastritis, and H. pylori grew from the sample. On day 14 he began antibiotics. He published the account in 1985.

The bacterium survives where others cannot by making large amounts of an enzyme called urease. It breaks down urea into ammonia and bicarbonate, which neutralise the acid in a small pocket around the bacterium.

The evidence grew, and the idea moved from the fringe into the textbooks. In 2005 Marshall and Warren shared the Nobel Prize in Physiology or Medicine for discovering H. pylori and its role in gastritis and peptic ulcers.

Not everyone who carries the bacterium gets sick. More than half the people in the world are thought to carry it, and most never have symptoms or complications. But for those who do develop an ulcer, the cause can now be tested for and treated, rather than blamed on nerves.

It is a reminder that an explanation everyone repeats is not the same as one that has been tested.