Figure 1: Serum Tobramycin and Creatinine Levels. Serum tobramycin and creatinine levels trended from surgical implantation of the antibiotic spacer on 10/5, to 3 sessions of dialysis on 10/11, 10/12, and 10/13, to explanation and replacement with a 4 g cephazolin spacer on 10/17.