Ampicillin therapy of experimental enterococcal endocarditis

Area of Science:

• Infectious Diseases
• Pharmacology
• Veterinary Medicine

Background:

• Enterococcal endocarditis is a serious infection.
• Current treatment often involves prolonged intravenous antibiotic therapy.
• The necessity of maintaining high serum bactericidal titers is debated.

Purpose of the Study:

• To evaluate the efficacy of intra-chamber ampicillin therapy for experimental enterococcal endocarditis in rabbits.
• To assess the relationship between therapy duration, bacterial load, and serum antibiotic concentrations.
• To determine if combination drug therapy is essential for treating this condition.

Main Methods:

• Rabbits with experimental enterococcal endocarditis received ampicillin via subcutaneously implanted perforated polyethylene chambers.
• Therapy duration varied, and vegetation cultures were performed.
• Serum and chamber fluid ampicillin concentrations and minimal bactericidal titers were measured.

Main Results:

• 21 days of intra-chamber ampicillin therapy sterilized vegetations in all rabbits.
• Shorter treatment durations showed an inverse relationship between therapy length and bacterial load.
• Peak serum bactericidal titers were high, while trough titers were low, yet effective.
• Mean trough serum ampicillin concentration exceeded the minimal bactericidal concentration for the infecting enterococcus.

Conclusions:

• Intra-chamber ampicillin administration is a viable strategy for treating experimental enterococcal endocarditis.
• Prolonged therapy duration is crucial for complete sterilization of vegetations.
• The requirement for maintaining high serum minimal bactericidal titers throughout therapy may be reconsidered.