[Antibiotic concentrations in the abdominal cavity as basis for antibacterial therapy of peritonitis: penetration of mezlocillin into the peritoneal exudate].

The importance of the antibiotic concentration in peritoneal exudate is emphasized as a criterium for the possible success of antibiotic therapy of intra-abdominal infections. 5 g of mezlocillin were given i. v. over 15 min to ten patients with a mean age of 56 years. The serum concentrations, assayed microbiologically, were: 299.5 mg/l at the end of the infusion, 103.2 mg/l, 18.6 mg/l and 2.1 mg/l 60, 240 and 480 min after the end of the infusion, respectively. The serum half-life T1/2 beta, calculated from the beta phase, was 67 min. In the peritoneal fluid the peak concentration of Cp = 42.0 mg/l was achieved after 2.2 h. A quarter of this concentration was maintained in the peritoneal cavity for five to six hours. This concentration inhibited 74% of the 322 pathogens isolated from 123 intra-abdominal infections.