Disinfection of human heart valve allografts with antibiotics in low concentration

Antibiotic disinfection of allograft heart valves is now an established procedure. A new low-concentration, broad-spectrum mixture of antibiotics was formulated and used successfully to disinfect 58 of 60 human aortic and pulmonary valves after 48 h exposure at 4 degrees C. The antibiotics included were cefoxitin 240 mcg/ml, lincomycin 120 mcg/ml, polymyxin B 100 mcg/ml, vancomycin 50 mcg/ml and amphotericin B 25 mcg/ml. Microorganisms isolated from experimental tissue and from clinical valves before treatment were tested for sensitivity to these antibiotics and were found to be sensitive to one or more. One isolate of Pseudomonas spp. showed decreased sensitivity to polymyxin B, and was found to have a minimum bactericidal concentration of 70 mcg/ml. Results indicated this antibiotic mixture had superior antibacterial efficiency to that in routine clinical use for the past 13 yr.