Alphabet unit Waymo said on Monday it has gone fully autonomous in Nashville, Tennessee, ramping up operations as the robotaxi race heats up in the United States.

In 1928, a chance contaminant in Scottish physician Alexander Fleming’s lab experiment led to a discovery that would change the field of medicine forever: penicillin. Since then, penicillin and other antibiotics have saved millions of lives. With one problem: the growing threat of antibiotic resistance. Today on Short Wave, host Regina G. Barber talks to biophysicist Nathalie Balaban about the conundrum — and a discovery her lab has made in bacteria that could turn the tides.Check out our episodes on extreme bacteria in Yellowstone and the last universal common ancestor. Interested in more science behind our medicines? Email us your question at [email protected] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.This episode was produced by Berly McCoy, edited by our showrunner Rebecca Ramirez and fact checked by Tyler Jones. Jimmy Keeley was the audio engineer.