PENETRATION OF CEFTRIAXONE (1 OR 2 GRAMS INTRAVENOUSLY) INTO MEDIASTINAL AND CARDIAC TISSUES IN HUMANS

Penetration of ceftriaxone into heart tissues (valves, myocardium, aur icles, and pericardium) and mediastinal tissues (fat and sternal bone) was evaluated after two regimens of ceftriaxone administration. Ten p atients (group I) were given 1,000 mg of ceftriaxone intravenously 30 min before anesthesia. Ten other patients (group 2) received the same dose and then a second 1,000-mg dose at the time of initiation of card iopulmonary bypass. Similar and very satisfactory penetrations of ceft riaxone into tissue were observed for both groups. During opening and closure of the thorax, mean ceftriaxone concentration was in excess of the MIC at which 90% of the potential pathogens were inhibited (great er than or equal to 4 mu g/g) in the thoracic fat, the sternal bone, a nd the pericardium. No significant differences between the two adminis tration regimens in penetration of ceftriaxone into tissue were observ ed. During cardiopulmonary bypass, the ceftriaxone concentration was g reater than or equal to 4 mu g/g in the myocardium, the endocardium, a nd the auricle. The regimen of ceftriaxone administration did not sign ificantly influence penetration of the drug into heart tissues. Howeve r, for some patients in the two groups and mainly in the sternal bone at the time of thorax closure (6 patients in group 1 and 5 patients in group 2), ceftriaxone levels in tissues were less than the MICs (4 mu g/g) for some potential pathogens (methicillin-susceptible Staphyloco ccus aureus and methicillin-susceptible Staphylococcus epidermidis). D uring the different steps of the surgical procedures, all (10 of 10) p atients in each group had tissue ceftriaxone levels greater than the M ICs for gram-negative aerobic bacilli (0.1 mu g/g), except for Pseudom onas spp.