Biochemical and pharmacodynamic studies of simple renal cyst fluids in relation to infection.

Biochemical analysis of renal cyst fluid was performed in 53 patients with simple renal cysts including 2 infected cases. The composition of noninfected cyst fluid tended to parallel that of serum. Additionally, the penetration of amikacin into cyst fluid was studied in 2 infected and in 11 noninfected patients following a single 200-mg intramuscular injection of amikacin. Drug levels in the fluid were below detection limit in the noninfected and approximately half or less of the serum values in the infected patients. These data may explain one of the reasons why infection of simple renal cysts is highly resistant to antimicrobial chemotherapy. The value of treatment by percutaneous aspiration and drainage of infected cysts is emphasized.