[Urinary tract infection associated with urinary calculi. 2. Effects of antibiotics on bacteria within infected stones].

We investigated the effect of antimicrobial agents against bacteria within infected stones. Cefmetazole (CMZ) was found to have equally strong activities against gram-positive and gram-negative bacteria isolated from the stones. In addition, CMZ was excreted in the urine from the affected kidney in high concentrations and was penetrated into the stone to some extent in vitro. However, preoperative administration of CMZ did not so significantly eradicate bacteria within the stones. Stones may function as a sanctuary for organisms and may attenuate the effects of antibiotics against them. Therefore, to treat urinary tract infection associated with urinary calculi, complete extirpation is necessary. In recent years, ultrasonic and other types of stone crushing methods are in wide use. CMZ or other effective antibiotics may become useful for the perioperative management of infected urinary stones.