Iron is an essential nutrient for the survival of most bacteria and participates in many important life processes. Pathogens have evolved multiple mechanisms to acquire iron from the infected host. However, excess iron will produce cytotoxicity via the Fenton reaction; thus, iron concentration must be strictly regulated. In order to limit infection, the host has evolved a variety of strategies to restrict iron availability to invading microbes. Targeting microbial iron acquisition systems is therefore a promising antibacterial therapy strategy.