Researchers from ETH Zurich, the Princeton Environmental Institute (PEI), and the Free University of Brussels gathered nearly 1,000 publications and unpublished veterinary reports from around the world to create a map of antimicrobial resistance in low- to middle-income countries. They focused on the bacteria Escherichia coli, Campylobacter, Salmonella, and Staphylococcus aureus, all of which cause serious disease in animals and humans.