Bioactive antibiotic levels in the human aorta.

A new bioassay was used to determine the level of active antibiotic within the aortic wall in 24 patients undergoing elective aortic surgery involving prosthetic grafts. The patients were divided into three groups and received either cefazolin, clindamycin, or cefoxitin intravenously at the induction of general anesthesia. Cefazolin and cefoxitin attained satisfactory tissue levels. Clindamycin did not reach therapeutic levels in the aortic wall. Blood levels did not correlate well with tissue levels.