Few therapeutic options are available for endocarditis due to enterococci that are resistant to high levels of gentamicin and streptomycin; no synergistic cell wall-active drug / aminoglycoside combination exists for endocarditis due to such strains, but the combination of the cell wall-active drugs ampicillin and ceftriaxone has recently been shown to be effective and minimizes the risk of nephrotoxicity.