By Malcom Ritter,AP Science Writer

Two Australians won the Nobel Prize in medicine Monday for a discovery that defied decades of medical dogma and revolutionized the treatment of ulcers. They showed that bacterial infection – not stress – causes ulcers in the stomach and intestine.

The 1982 discovery by Drs. Barry Marshall and Robin Warren eventually transformed peptic ulcer disease from a chronic, frequently disabling condition to one that can be cured by a short regimen of antibiotics and other medicines, said the Nobel Assembly of the Karolinska Institute in Stockholm.

Marshall, 54, and Warren, 68, discovered the bacterium Helicobacter pylori and uncovered its role in causing ulcers and stomach inflammation. The prize, with its $1.3 million check, gives the ultimate validation to an idea that initially drew skepticism and derision.

The Australians’ bacterial theory of ulcers was “very much against prevailing knowledge and dogma,” Staffan Normark, a member of the Nobel Assembly, said at a news conference in Stockholm. Most doctors believed ulcers came from stress and stomach acid.

To make his case, Marshall even deliberately infected himself by swallowing a culture of H. pylori.

“I developed a vomiting illness and had severe inflammation in the stomach for about two weeks,” he told The Associated Press. “I didn’t actually develop an ulcer, but I did prove that a healthy person could be infected by these bacteria, and that was an advance because the skeptics were saying that people with ulcers somehow had a weakened immune system and that the bacteria were infecting them after the event.”

He and Warren believed the bacteria came first, causing inflammation, then ulcers. The experiment helped establish that.

Warren, a retired pathologist, said it took a decade for others to accept their findings.

The long-standard teaching in medicine was that “the stomach was sterile and nothing grew there because of corrosive gastric juices,” he said. “So everybody believed there were no bacteria in the stomach.”

“When I said they were there, no one believed it,” he added.

The two researchers began working together in 1981. “After about three years we were pretty convinced that these bacteria were important in ulcers and it was a frustrating time for the next 10 years though because nobody believed us,” said Marshall, a researcher with the University of Western Australia.

“The idea of stress and things like that was just so entrenched nobody could really believe that it was bacteria. It had to come from some weird place like Perth, Western Australia, because I think nobody else would have even considered it.”

Dr. David A. Peura, president of the American Gastroenterological Association, said the prize-winning work “revolutionized our understanding of ulcer disease” and “gave millions of people hope.”

He read about the H. pylori theory in 1983 while serving as a gastroenterologist in the Army, and “I thought it was crazy,” he recalled Monday.

But he and a colleague were intrigued, and soon they discovered they could cure ulcers in their own patients with antibiotics targeted at H. pylori.

“It was such an intriguing theory that everybody tried to disprove it and couldn’t, so we all became believers,” said Peura, now a professor of medicine at the University of Virginia at Charlottesville.

Peura, who met Marshall when both worked at Virginia and considers him a friend, said Marshall’s perseverance was responsible for the eventual acceptance of the theory. “Any lesser of a person probably would not have been able to withstand some of the ridicule and scorn that was thrown at him initially,” Peura said.

As the two Nobel winners celebrated with family over champagne and beer in Perth, the Western Australia state capital, Warren said he was “very excited, also a little overcome.”

“Obviously, it’s the best thing that can ever happen to somebody in medical research. It’s just incredible,” added Marshall in a telephone interview.

Their work has stimulated research into microbes as possible causes for other chronic inflammatory conditions, such as Crohn’s disease, ulcerative colitis, rheumatoid arthritis and atherosclerosis, the Nobel assembly said in its citation.

The discovery came about after Warren had observed bacteria colonizing the lower part of the stomach of patients and noted that signs of inflammation were always present close to the bacteria. Marshall became interested in Warren’s findings and together they launched a study of more patients.

Marshall also succeeded in cultivating the previously unknown bacterium from patient biopsies, in part because he accidentally left a sample in his lab over the Easter holiday in 1982 – unwittingly giving his cultures time enough for success.

Together, the two men found H. pylori present in almost all patients with stomach inflammation or ulcers in the stomach or the part of the small intestine called the duodenum.

The Nobel prize in physics will be awarded Tuesday and the chemistry prize on Wednesday. Those for literature, peace and economics will follow.

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Medical writer Emma Ross in London contributed to this report.

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On the Net:

Nobel Prizes: www.nobelprize.org

Marshall Web site: www.eftelcorporate.com.au/ 7/8bjmrshll/