The Risk of Persistent Bacteriuria after Extracorporeal Shock Wave Lithotripsy of Infection Stones: A Prospective Study

Extracorporeal shock wave lithotripsy (ESWL) effectively pulverizes infected (struvite) renal calculi. However, after ESWL minute residual fragments which may harbor bacteria and cause persistent bacteriuria can remain in the renal collecting system for months. We investigated prospectively the incidence of persistent Proteus mirabilis bacteriuria after ESWL among 20 consecutive women with P. mirabilis urinary tract infections and struvite calculi. All patients received parenteral gentamicin for three to 13 (mean 4.9) days immediately before and after ESWL. Oral antimicrobials were then administered for 14 to 70 (mean 31) days. Fifteen patients maintained a sterile urine or experienced urinary reinfection by other organisms during five to 22 (mean 14) months of subsequent bacteriologic surveillance. Nine of these 15 patients had residual fragments at last follow-up. Five patients developed P. mirabilis bacteriuria after one to seven months of surveillance. Three of these five patients had residual fragments. The mean stone size, methods of and duration of renal drainage procedures, and duration of antimicrobial therapy were similar for the two patient groups. P. mirabilis was isolated from the cultures of only three of 16 retrievable stone fragments. In contrast to intact infected renal calculi, residual stone fragments after ESWL are often susceptible to sterilization with antimicrobials.