Penetration of penicillin into laparotomy wounds to reduce bacterial contamination during intestinal operations

Serum and tissue specimens from the surgical wound were taken simultaneously during colo-rectal operations (i) at the start, (ii) when entering the peritoneal cavity, (iii) during bowel procedures and (iv) before closure of the wound. A dose of 5 megaunits penicillin intravenously after incision gave a median serum concentration of 140.0 IU/ml and a tissue concentration of 33.8 IU/mg at the time the peritoneum was incised. During operation the concentration in serum fell significantly, being 18.5 IU/ml after more than 3 h of operation, while that in wound tissue decreased to 7.2 IU/mg. After concentration was 16.0 IU/ml in serum and 1.9 IU/mg in wound tissue at the time of incision and when entering the peritoneal cavity; thereafter the concentrations decreased with operation time. The concentrations in serum exceeded markedly those in wound tissue, being linearly correlated throughout operation. Only the intravenous bolus produced concentrations of penicillin antibacterial to a variety of aerobic organisms.