MEDICAL-TREATMENT OF INFECTIVE ENDOCARDITIS - GENERAL-PRINCIPLES

The main objective of medical treatment of infective endocarditis is t o sterilize the vegetative lesions characteristic of the disease. The general principles of treatment are: (1) identification of the causati ve organism; (2) in vitro determination of its susceptibility, and (3) the choice of a bactericidal treatment. In vitro susceptibility, the minimum inhibitory concentration (MIC)/minimum bactericidal concentrat ion (MBC) rate, the level of aminoglycoside resistance and in vitro sy nergy testing activity, generally a cell-wall-active agent and an amin oglycoside. Treatment must be instituted parenterally, to ensure compl ete bioavailability, high serum concentrations and good penetration in to the vegetations. The mode of administration depends on the organism , the serum-half-life and the mode of antimicrobial effect whether tim e or concentration-dependent, and the post-antibiotic effect (PAE). Ce ll-wall-active antibiotics (beta-lactams and glycopeptides) with a tim e-dependent activity require concentrations above MIC for as long as p ossible between administrations mainly if there is no PAE; concentrati on five to ten times the MIC. Therapy must be monitored rigorously The clinical relevance of serum bactericidal titre is poor owing to lack of standardization and its poor predictive value of failrtre. The dura tion of therapy must be sufficient (4-6 weeks) to prevent failure or r elapse.