Endocarditis (infection of the inside the heart) is a fatal disease that requires prompt antibiotic therapy. Many different kinds of bacteria can cause endocarditis, including a bacterium known as Enterococcus faecalis (or E. faecalis). The American Heart Association recommends that E. faecalis endocarditis be treated with a combination of antibiotics that includes either penicillin or ampicillin and an aminoglycoside antibiotic. Unfortunately, some strains of E. faecalis, known as HLAR (high-level aminoglycoside resistance) E. faecalis, are resistant to aminoglycoside antibiotics, and the recommended combination of antibiotics does not cure infection with these strains. In addition to problems of resistance, aminoglycoside antibiotics can sometimes cause kidney damage. As a result, doctors try to avoid using aminoglycosides in patients with decreased kidney function. Doctors have been searching for an effective combination of antibiotics to treat patients with endocarditis caused by HLAR E. faecalis and those with decreased kidney function. Animal experiments have suggested that the antibiotic combination of ampicillin plus ceftriaxone might be effective against HLAR E. faecalis endocarditis while avoiding kidney damage caused by aminoglycosides.