Interaction of intracorporeal lithotripters with Proteus mirabilis inoculated inside artificial calcium and struvite stones.

BACKGROUND AND PURPOSE

Renal calculi may contain bacteria that can remain active inside the stone and produce bacteremia and/or endotoxemia after lithotripsy. Urinary tract infection associated with urinary stones represents high morbidity. The purpose of this research was to use novel artificial struvite stones inoculated with living bacteria and to study the effect of four different intracorporeal lithotripters on bacterial inactivation after in vitro lithotripsy.

MATERIALS AND METHODS

Two types of artificial kidney stone models (calcium sulphate and mixed struvite-calcium sulphate) were manufactured and infected with Proteus mirabilis. Stones were fractured using either electrohydraulic, laser, ultrasonic, or pneumatic lithotripters. Bacterial viability was determined before and after the lithotripsy.

RESULTS

Bacterial inactivation was not affected by the stone matrix; ie, calcium or struvite. The four tested lithotripters were almost equally efficient at reducing the viability of P mirabilis in both the low and the high energy setting.

CONCLUSIONS

We were able to obtain novel artificial struvite stones infected with bacteria. Intracorporeal lithotripters are efficient at reducing the viability of P mirabilis in vitro. Tested stone materials play a minor role regarding inactivation. Whether the bactericidal effect reported is desirable or not is still to be answered, because the presence of endotoxin from cell lysis may increase the risk of urosepsis.