 Enterococcus facalis is a gram-positive commensal bacterium that can cause serious illness when exposed to certain conditions. It produces a poor-forming toxin called cytolicin, which is capable of killing both bacterial and eukaryotic cells. This toxin was first discovered in the 1930s and has since been studied extensively. Recently, new technologies have allowed researchers to gain a better understanding of how cytolicin works and its potential applications. This article was authored by Daria van Tijn, Melissa J. Martin and Michael S. Gilmore.