The bacteriology of the urine and renal calculi.

The bacteriological status of the pre-operative urine, removed calcium and the pelvic urine was studied in 63 consecutive patients undergoing removal of intrarenal calculi. The overall infection rates in the pre-operative urine, removed calculi and pelvic urine were 29%, 38% and 30% respectively. In patients with staghorn calculi, 58% of patients had an infected pre-operative M.S.S.U., and 82.5% of removed calculi demonstrated significant bacterial growth, with Proteus mirabilis being the predominant organism isolated. In patients with single or multiple oxalate calculi, 17% had an infected pre-operative M.S.S.U., and 22% of removed calculi demonstrated a significant bacterial growth. The findings would indicate that the presence of a positive M.S.S.U. in a patient with a renal calculus is an indication for surgical removal.