Therapeutic Targeting of the Staphylococcus aureus Accessory Gene Regulator (agr) System

<i>Staphylococcus aureus</i> can cause numerous different diseases, which has been attributed to its large repertoire of virulence factors, many of which are under the control of the accessory gene regulator (<i>agr</i>) quorum sensing system. Under conditions of high cell density, <i>agr</i> increases the production of many virulence factors, decreases expression of several colonization factors, and is intimately associated with the pathogenesis and biofilm formation of <i>S. aureus</i>. This review summarizes our current understanding of the molecular mechanisms underlying <i>agr</i> quorum sensing and the regulation of <i>agr</i> expression. The discussion also examines subgroups of <i>agr</i> and their association with different diseases, and concludes with an analysis of strategies for designing drugs and vaccines that target <i>agr</i> to combat <i>S. aureus</i> infections.