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Mechanisms of Successful Amoxicillin Prophylaxis of Experimental Endocarditis Due to Streptococcus intermedius

Moreillon, P. ; Francioli, P. ; Overholser, D. ; Meylan, P. ; Glauser, M. P.

In: Journal of Infectious Diseases, 1986, vol. 154, no. 5, p. 801-807

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    Title
    • Mechanisms of Successful Amoxicillin Prophylaxis of Experimental Endocarditis Due to Streptococcus intermedius
    Author
    • Moreillon, P.. Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
    • Francioli, P.. Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
    • Overholser, D.. Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
    • Meylan, P.. Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
    • Glauser, M. P.. Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Journal of Infectious Diseases, 1986, vol. 154, no. 5, p. 801-807. The University of Chicago Press
    Other Version
    Classification
    • Health
    OAI-PMH Identifier
    • oai:doc.rero.ch:300515
    Summary
    Prophylaxis with amoxicillin (40 mg/kg) was studied in rats with aortic valve vegetations. Bacteria on the valves were quantitated early (10 min to 6 hr) and late (three days) after intravenous challenge with tolerant Streptococcus intermedius. Amoxicillin reduced by 40% the number of bacteria per valve 10 min after intravenous challenge with 105 S. intermedius (P < .05) and by 74% the incidence of endocarditis three days thereafter (P < .0001). Bacterial multiplication started 2 hr after challenge in control rats, whereas bacteria disappeared in 6 hr in amoxicillin-treated rats. Intravenous penicillinase 30 min after challenge abolished successful amoxicillin prophylaxis, a result demonstrating the necessity of prolonged growth inhibition for protection. Growth inhibition for 18 hr (two subsequent amoxicillin doses) was necessary for protection after intravenous challenge with 105 S. intermedius. Thus, in the absence of bacterial killing, inhibition of valvular colonization by amoxicillin was not as important a mechanism of endocarditis prophylaxis as was prolonged inhibition of bacterial growth, which allowed adherent bacteria to be cleared from the valves