Dr. Robert Gaynes, distinguished physician and professor of infectious diseases at Emory University, joins Meet the Microbiologist for the 3rd , and final, episode in a unique 3-part segment, in which we share stories about the life and work of medial pioneers in infectious diseases. Here we discuss the career of Dr. Barry Marshall, the Australian physician who is best known for demonstrating in a rather unorthodox way that peptic ulcers are caused by the bacterium, Helicobacter pylori. Gaynes is author of Germ Theory: Medical Pioneers in Infectious Diseases, the 2nd edition of which will publish in Spring 2023. All 3 scientists highlighted in this special MTM segment are also featured in the upcoming edition of the book.