Proteus mirabilis viability after lithotripsy of struvite calculi

Purpose: We tested the hypotheses that Proteus mirabilis viability of struv ite calculi differs after exposure to different Lithotripsy modalities and that the photothermal mechanism of holmium:YAG Lithotripsy is antibacterial . Materials and Methods: Human calculi of known struvite composition (greater than 90% magnesium ammonium phosphate hexohydrate) were incubated with P. mirabilis. Calculi were randomly distributed and fragmented with no lithotr ipsy (controls), or shock wave, intracorporeal ultrasonic, electrohydraulic , pneumatic, holmium:YAG or pulsed dye laser lithotripsy. After lithotripsy fragments were sonicated and specimens were serially plated for 48 hours a t 38C. Bacterial counts and the rate of bacterial sterilization were compar ed. Results: Median bacterial counts (colony-forming units per mi.) were 8 x 10 (6) in controls and 3 x 10(6) in shock wave, 3 x 10(7) in ultrasonic, 4 x 1 0(5) in electrohydraulic, 8 x 10(6) in pneumatic, 5 x 10(4) in holmium:YAG and 1 x 10(6) in pulsed dye laser lithotripsy cases (p <0.001). The rate of bacterial sterilization was 50% for holmium:YAG lithotripsy treated stones versus 0% for each of the other cohorts (p <0.01). Conclusions: P. mirabilis viability varies among lithotrites. The photother mal mechanism of holmium:YAG lithotripsy is antibacterial.