Barry Marshall

University of Western Australia

Barry James Marshall is an Australian physician-scientist at the University of Western Australia who, together with pathologist Robin Warren, discovered that most peptic ulcers and gastric cancers are caused by the bacterium Helicobacter pylori. Before this discovery, peptic ulcers were widely believed to result from stress and excess acid, and treatment was symptomatic. Marshall famously drank a broth containing H. pylori to fulfill Koch's postulates, giving himself gastritis and demonstrating that the bacterium was pathogenic. He then showed that a short course of antibiotics could cure ulcers permanently — a paradigm shift in gastroenterology. Marshall and Warren shared the 2005 Nobel Prize in Physiology or Medicine. This discovery transformed the treatment of peptic ulcer disease from lifelong acid suppression therapy to a curative antibiotic regimen, eliminated hundreds of thousands of surgeries annually, and ultimately revealed H. pylori as a major risk factor for gastric adenocarcinoma — linking a chronic bacterial infection to cancer.