Antibiotic activity in peritoneal dialysate.

There are few studies investigating whether antibiotics added to 30% glucose concentrate preserve their activity in the delivered dialysate. Using a Drake-Willock proportioning system, samples were obtained from the "to" patient path at ten minutes after starting and at four hours. Samples were tested for minimal inhibitory dilution (MID) against Escherichia coli and Staphylococcus aureus. Antibiotics evaluated included amikacin, tobramycin, gentamicin, cephalothin, cefamandole, moxalactam, ampicillin, penicillin, carbenicillin, and vancomycin. In all antibiotics studied, similar MIDs were obtained at the ten-minute and four-hour samples. Compared to saline, dialysate significantly impaired the antibiotic activity (a difference of two or more tube dilutions) of all antimicrobial agents except amikacin and vancomycin.