Penicillin concentrations in abdominal operation wounds after intravenous administration

The concentration of benzylpenicillin has been studied in serum and in homogenates of the subcutaneous tissue from abdominal operation wounds in 13 patients who underwent surgery of the colon and/or rectum. An intravenous bolus of 5 megaunits benzylpenicillin gave rise to a serum median concentration of 128.0 i.u./ml and a corresponding tissue median concentration of 29.6 i.u./ml in the operation wound. The serum concentration never fell below the tissue level in sequential periods, and a significant correlation between the concentrations in serum and tissue supports a hypothesis of penetration of penicillin into the wound tissue by diffusion. The results indicate that administration of benzylpenicillin initiated at the time of colo-rectal surgery ensures concentrations in the operation wound inhibitory to a variety of contaminating bacteria, thus being an adjunct to the tissue defences in combating the development of postoperative wound infection.