Ampicillin plus ciprofloxacin therapy of experimental endocarditis caused by multidrug-resistant Enterococcus faecium.

The combination of ampicillin and ciprofloxacin displayed bactericidal in-vitro activity against two strains of Enterococcus faecium which were highly resistant to ampicillin, vancomycin, and aminoglycosides. This antibiotic combination was used to treat rabbits with experimental endocarditis caused by these strains. Although a significant decrease in vegetation bacterial counts occurred with one strain, the degree of killing did not approach that of penicillin with an aminoglycoside against susceptible enterococci.