Staphylococcus aureus is an opportunistic Gram-positive pathogen capable of causing a wide range of infections. Currently, there is a constant need for new drugs to fight infections caused by antibiotic-resistant S. Aureus. The use of proteins and peptides (parts of proteins) as antimicrobial agents is inspired by nature, and has recently attracted attention as an antibiotic-free approach to treat bacterial infections. Lysostaphin is a special type of protein (enzyme) that cuts through specialized structures in the cell wall, breaking the wall and killing the bacteria. Attaching these antibacterial enzymes to biodegradable and biocompatible polymer nanoparticles makes the enzyme more stable than free enzymes, and could be used to deliver the enzyme directly to the site of infection. This image is part of a study comparing the antimicrobial activity of lysostaphin on the surface of polylactic acid (PLA) nanoparticles with that of the free enzyme. These enzyme-nanoparticles could become a new treatment for antibiotic-resistant S. Aureus infections.