Is penicillin alone effective in enterococcal endocarditis? An experimental study in rabbits

Area of Science:

• Infectious Diseases
• Pharmacology
• Cardiology

Background:

• Enterococcal endocarditis is typically treated with a combination of penicillin and an aminoglycoside.
• The efficacy of penicillin monotherapy for enterococcal endocarditis remains incompletely understood.
• Untreated experimental enterococcal endocarditis in rabbits is uniformly fatal within two weeks.

Purpose of the Study:

• To evaluate the effectiveness of penicillin monotherapy in treating experimental enterococcal endocarditis.
• To determine optimal penicillin dosing strategies for enterococcal endocarditis.

Main Methods:

• Induction of experimental enterococcal endocarditis in male New Zealand rabbits.
• Administration of varying doses and types of penicillin (crystalline penicillin G and procaine penicillin).
• Assessment of mortality rates and evaluation of penicillin levels in serum and myocardium.

Main Results:

• Crystalline penicillin G at 30,000 U/day and 600,000 U/day resulted in high mortality rates (63.3% and 37.5%, respectively).
• Procaine penicillin at 300,000 U/day showed some protection but still had significant mortality (17.5%).
• A higher dose of procaine penicillin (600,000 U/day) completely protected rabbits from mortality.

Conclusions:

• Penicillin alone, particularly crystalline penicillin G, is ineffective for treating enterococcal endocarditis.
• High-dose procaine penicillin, achieving sustained therapeutic levels, is effective in curing experimental enterococcal endocarditis.
• Achieving high and sustained penicillin concentrations in serum and myocardium is crucial for successful treatment.