The modulation by fresh and spent peritoneal dialysis fluids of antibiotic kinetics directed against Staphylococcus epidermidis biofilms.

The presence of CAPD peritoneal catheters has an association with S. epidermidis infections which are relatively resistant to antibiotic therapy. This resistance has been ascribed to the formation by the bacteria of a protective matrix on the catheter surface enclosing the bacteria to form a bacterial biofilm. The rate of action of 14 antibiotics on standardized S. epidermidis bacterial biofilms over a 5 day exposure period and the modifying effects of fresh and spent peritoneal dialysis fluids were assayed. There were significant differences in the rates of antibiotic action. Fresh dialysis solution markedly augmented rifampin activity, and to a lesser extent, vancomycin, cloxacillin and teicoplanin but antagonized ciprofloxacin. Spent dialysis fluid generally augmented the activity of antibiotics, notably cloxacillin and cephalothin. Rifampin was bactericidal in both fresh and spent dialysis fluids. Fusidic acid was a poor performer in all tests.