Antibiotic resistance of the bacterium Staphylococcus aureus is responsible for 11,300 deaths a year in the United States alone—a figure that corresponds to half of all deaths caused by gram-positive resistant bacteria in that country. Such high mortality is related to the speed at which the bacterium acquires resistance to antibiotics. A study performed at the Institute for Research in Biomedicine (IRB Barcelona) and involving the collaboration of the Centro de Investigaciones Biológicas (CIB-CSIC) in Madrid has identified the key component of the machinery that S. aureus uses to acquire and transfer genes that confer resistance to antibiotics. The work has been published this week in the Proceedings of the National Academy of Sciences (PNAS).