Antibiotics in biliary disease: the relative importance of antibiotic concentrations in the bile and serum.

A randomised controlled trial has been performed in 150 patients undergoing biliary operations to determine whether an antibiotic which is excreted almost entirely in bile (rifamide) is to be preferred to one having satisfactory serum levels only (gentamicin). Patients were allocated to one of three groups: 50 received gentamicin, 50 received rifamide, and there were 50 controls who received no antibiotic cover. In the absence of duct obstruction, rifamide achieved extremely high bile levels but low serum concentrations. However, in jaundiced patients, both the bile and the serum concentrations of rifamide were too low to be of therapeutic value. The incidence of postoperative sepsis was not reduced by rifamide compared with controls. In contrast, gentamicin achieved adequate serum concentrations in 88% of patients. Despire poor bile levels, gentamicin was associated with a significant reduction of wound infection from 22% to 6% and septicaemia from 14% to 2% compared with controls. To reduce the septic complications of biliary operations, adequate serum levels of an effective antimicrobial are more important than an antibiotic, which is excreted almost entirely into the bile.