The administration of "active" chondroitin sulfate A (CSA), "active" chondroitin sulfate C (CSC), or mixtures thereof to mammals including humans suffering from cancer, bacterial infections, trauma, irritation, placement of foreign objects, tubes or instruments, or damage of the upper or lower urinary tract, and related transitional cell surfaces to prevent cancer cell implantation or adherence, bacterial infestation or adherence, trauma, irritation, or damage from placement of foreign objects, tubes or instruments in the kidney, renal pelvis, ureter, bladder, urethra and related transitional cell surfaces by the irrigation of said surfaces and/or tubes and instruments with a solution of said drugs or mixtures thereof.