In vivo efficacy of azlocillin and amikacin versus ciprofloxacin with and without amikacin in experimental right-sided endocarditis due to Pseudomonas aeruginosa

The efficacy of azlocillin + amikacin was compared to ciprofloxacin (with and without amikacin) in 96 rabbits with right-sided endocarditis due to Pseudomonas aeruginosa. Animals received either: (1) no therapy (controls); (2) amikacin (15 mg/kg/ day) + azlocillin (400 mg/kg/day); (3) ciprofloxacin (80 mg/kg/day) or (4) amikacin + ciprofloxacin (above dosages). All three antibiotic regimens were significantly more effective than no therapy in reducing mortality (p < 0.0005), preventing pulmonary infarction (p < 0.0005) and reducing mean vegetation titers of P. aeruginosa (p < 0.0005). Also, the three therapy regimens were equivalent in preventing bacteriologic relapse after discontinuing therapy. No development of antibiotic resistance in vivo was observed.