For Dr. Barry J. Marshall, medicine is a passion.

But that zest was meaningful only if it worked to help people.

As a young physician in training in Perth, Australia, in 1981, he found his pivotal moment when a female patient with stomach pain was packed off to a psychiatrist for "stress."

Since the 1930s, conventional medical wisdom held that ulcers were caused by excessive stomach acid brought on by stress.

Marshall figured the diagnosis was wrong. He had just learned that a suspect bacterium, Helicobacter pylori, discovered by Dr. J. Robin Warren, might have more to do with ulcers. If he and Warren could prove it, they could find a real cure.

Marshall thus spent a decade proving that Helicobacter pylori — not stress — is the real cause of ulcers.

To find a cure, Marshall researched on his own time, worked in obscure places and endure ridicule to bring the truth forward.

Ultimately, he decisively convinced the international medical establishment. He paved the way for a simple, permanent cure that ended the suffering of millions worldwide.

Marshall's and Warren's work revolutionized gastroenterology such that ulcers became totally curable and the doctors put the defeat of stomach cancer in sight.

For their effort, they were awarded the Nobel Prize in medicine in 2005.

Born the first son of a 19-year-old welder and an 18-year-old nursing student in 1951, in Kalgoorlie, Australia, Marshall early on showed a curiosity as broad and wild as the Australian outback, taking a cue from his family's ability to make the best of unexpected situations.

"After my father finished his apprenticeship, my parents decided to go and work in the new uranium mines in Rum Jungle in the Northern Territory," he wrote in his Nobel autobiography. "They drove their Model A Ford up Australia's west coast about 1,000 miles, but stopped at Carnavon when the car broke down."

Rather than complain, his father recognized that good jobs existed near a local whaling station and settled his the family there. They set up a household with dirt floors and an outhouse near the beach.

Marshall was only 2, but loved exploring the outdoors. He learned to make bows and arrows and became fascinated with a derelict steam engine near a railway, portending a lifelong interest in mechanics and technology that eventually gave him an edge in medical research.

As he grew older, he also loved experimenting with electronics and getting into his mother's medical books, reading them for fun.

Watching her son's broadening interests, Marshall's mother worried he might be sucked into the easy life of northern Australian mining settlements, where salaries were good and partying was a way of life.

She persuaded her husband to move the family to Perth to ensure that her son's energy would be channeled into education.

Marshall was a good student and won a medical scholarship to the University of Western Australia in 1968, finishing by 1974.

He married his wife, Adrienne, in 1972. A psychology student, she became his loyal collaborator, helping articulate his thoughts and letting him take poorly paid jobs so he could focus on his real research. She also offered critical support when skeptics questioned his work.

Marshall, 55, began training as a gastroenterology specialist in 1978. As a nonspecialist, his broad exposure to different fields gave him a powerful advantage for medical discoveries.

After he met Warren, a more senior researcher investigating the strange spiral bacteria found in those with stomach ulcers, they began looking at bacteria as a possible cause of ulcers because they lived in the stomachs of those with gastritis and peptic ulcer disease. They also were found in the stomachs of those able to resist infection; this was one reason the medical community dismissed bacteria.

No bacterium is strong enough to survive stomach acid, many said, so bacteria found in a biopsy were attributed to contamination.

But the two doctors began isolating the bacterium and conducting experiments on animals. They formed an enduring friendship, discussing the research over cigarillos.

Then Marshall's rotation in specialist training ended, and he had to move to a new hospital 1,000 miles north. But he couldn't abandon this research; it was crucial. He vowed to stay in contact with Warren and keep working — even if he had to do it on his own.Marshall took jobs at lower pay and at obscure institutions so he could find time to continue the Helicobacter research by corresponding with Warren.

In the dull medical jobs that were there only to support his family, Marshall found he had plenty of energy left in the evening to go further than his peers at fancier hospitals could. Why? He knew technology.

In the early 1980s, computers were just getting started. Marshall managed to build himself one at home to play with in the evenings.

He soon realized he had constructed a powerful research tool capable of communicating with other scientists around the world and accessing research papers from the world's best medical libraries.

Suddenly, he wasn't just an obscure doctor from Perth, but in touch with reams of research. He resembled one of the first Googlers, but with more rudimentary tools.

Marshall crunched the research to prove the bacterium's role in the cause of ulcers, and soon was able to grow some in a laboratory. In 1983, he presented his medical research at a conference in Belgium.

The scientists were quick to ridicule the young doctor and belittle his isolation of the bacterium, telling him it was benign.

Eventually, some of Marshall's harshest skeptics found that his research was sound — it did take just a simple prescription of bismuth and generic antibiotics over two weeks to destroy ulcers forever. Many became his biggest champions.

Marshall has since done research in the U.S., written a book called "Helicobacter Pioneers" on his early research and worked with vaccine companies.

Today he is a senior research fellow at the University of Western Australia, where he continues to pursue new discoveries.

BY MONICA SHOWALTER