Penetration of prophylactic antibiotics into peritoneal fluid

This study evaluates the penetration of cephalosporins into the peritoneal fluid. Forty-six patients scheduled for abdominal surgery were randomized into three groups. On call to the operating room each patient was given a single 1 g dose of cefazolin, cefuroxime, or ceftazidime. Samples of the peritoneal fluid and blood were simultaneously obtained immediately after opening the peritoneal cavity. The mean serum cefazolin concentration was the highest. High peritoneal fluid levels of all three antibiotics were found; however, the antibacterial activity against common intestinal pathogens varied significantly. Cefazolin is the only study drug that possesses marginal in vitro activity against Streptococcus faecalis, a species generally considered resistent to cephalosporins. This study suggests that prophylactic second and third generation cephalosporins are not superior to cefazolin.