Can washing your hands help stop the evolution of antibiotic resistance? Mathematically, it’s possible. While bacteria that are more sensitive to the antibiotics are killed off, those that are able to survive will continue to reproduce with less competition. This results in increasing abundance of resistant bacteria that can undermine the effectiveness of the antibiotic. Kristofer Wollein Waldetoft is a postdoctoral fellow in infection medicine for the Cystic Fibrosis Foundation and the School of Biological Sciences who researches in the lab of Sam Brown, professor and member of the Center for Microbial Dynamics and Infection. Woldetoft collaborated with Brown and other colleagues to develop a mathematical model of antibiotic resistance evolution to learn the role hygiene plays in that process.