A common chemical used to kill bacteria is making them more capable of surviving antibiotics.

First seen as a problem mainly confined to hospitals and nursing homes, research suggests C. diff rates in the community are on the rise, and that traditional risk factors may no longer tell the whole story.

On this encore edition of the 21st: Do you ever wonder if dirt really is good for kids? We explore how bacteria in our gut and all over our bodies affect our health. We also discuss a new book that explores how, before Roe v. Wade, some religious leaders formed a secret network to refer women to doctors for unwanted pregnancies. 

Bacteria are becoming increasingly resistant to antibiotics. David Hoffman has looked into this phenomenon and questions of food safety in three documentaries for Frontline.