My guest this week is Dr. Martin Blaser. I know Marty well due to his more recent work on antibiotics and their off-target impacts on the gut microbiome, described in his book "Missing Microbes". We discuss the origins of this work during his time tracking epidemics at the CDC, his love for the rare but fascinating Campylobacter fetus, and his seminal work on identifying a "symbiosis factor" for Helicobacter pylori.