[Penetration of vancomycin in cardiac and mediastinal tissues in humans]

Vancomycin penetration into heart tissues (valves, myocardium, auricles and pericardium) and mediastinal tissues (fat and sternal bone) after two regimens of administration was evaluated in a prospective, randomized study. Twenty adult patients undergoing mitral or aortic valve replacement were included in the study and divided into two groups of ten patients each: Group 1 patients were administered a 15 mg/kg intravenous dose of vancomycin over 90 min upon anesthesia. Group 2 patients received the same dose followed by a second 7.5 mg/kg intravenous dose of vancomycin over 30 min at time of initiation of the cardiopulmonary bypass. In both groups further vancomycin administrations (10 mg/kg) were performed on hour 8, 16 and 24. Plasma and tissue vancomycin concentrations were assayed by fluorescence polarization immunoassay. At different times of the surgical procedures (thorax opening and closure, period of cardiopulmonary bypass) 67 to 100% of the patients in group 1 had vancomycin concentrations in the studied tissues above the MIC 90 for Staphylococcus aureus (1 microgram/g) and Staphylococcus epidermidis (2 micrograms/g). In group 2, for the same periods and the same tissues, 72 to 100% of patients had adequate vancomycin concentrations. In group 1 patients, mean ratios of vancomycin tissue concentrations/MIC 90 were 6 +/- 2 to 20 +/- 4 for Staphylococcus aureus (MIC 90: 1 microgram/g) and 3 +/- 1 to 10 +/- 4 for Staphylococcus epidermidis (MIC 90: 2 micrograms/g). In group 2 patients, mean ratios were 8 +/- 3 to 20 +/- 4 for Staphylococcus aureus and 4 +/- 1 to 10 +/- 3 for Staphylococcus epidermidis. The use of a second dose of vancomycin in group 2 significantly increased plasma concentrations (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)