In vitro bactericidal effect of Ho:YAG laser and pneumatic lithotripsy on ureteral stones colonized with Escherichia coli and Enterococcus faecalis.

The endoscopic treatment of urolithiasis has a high success rate and the complications decreased after the development of lithotripsy techniques. The aim of this study is to investigate the in vitro bactericidal effect of laser and pneumatic lithotripsy on urinary stones colonized with Escherichia coli and Enterococcus faecalis. A total of 40 natural calcium oxalate stones, which were obtained from the patients' urinary systems with rigid ureteroscopy were used in the study. Surfaces of the stones were colonized with E. coli and E. faecalis strains. The fragmentation of the stones was performed using holmium:yttrium-aluminum-garnet laser (Ho:YAG laser) and pneumatic lithotripters in vitro in Eppendorf tubes filled with liquid. After fragmentation, samples taken from Eppendorf tubes were inoculated on blood and EMB agar. The number of colonies was evaluated after 18-24-hour incubation period. The laser lithotripsy technique reduced the number of colonies by 100% and had bactericidal effect on E. coli and E. faecalis. Pneumatic lithotripsy technique had no bactericidal effect on these strains (0%). In the fifth minute of laser irradiation, the average temperature in the Eppendorf tube was 51-55 °C, and the average temperature in the tenth minute was 54-60 °C. The temperatures did not change in the fifth and tenth minutes with the pneumatic lithotripsy procedure. The present study revealed the bactericidal effect of Ho:YAG laser on E. coli and E. faecalis in vitro. Increased ambient temperature during Ho:YAG laser lithotripsy is thought to play a role in the bactericidal effect. But the question of whether an ideal lithotripter efficiently inactivates or destroys bacteria has still not been answered in urology practice. This preliminary study showed the bactericidal effect of Ho:YAG laser lithotripsy, but further studies are needed to investigate the bactericidal effect of Ho:YAG laser in vivo.