Infection related to inserted or implanted medical devices (“biomaterials”) is a major problem. These infections are often caused by aggregates of microorganisms embedded within a self-produced matrix of extracellular substance adhering to biomaterials (biofilms) and by bacteria surviving in tissue surrounding the implanted biomaterial. Biofilms are notoriously resistant to antibiotics and there currently is no effective strategy to control biofilm formation. Similarly, bacteria in the surrounding tissue are difficult to target, partly because they may be localized within host cells. As a result biomaterial-associated infections cannot be prevented or adequately treated.