In vitro and in vivo study of stone formation by Corynebacterium group D2 (Corynebacterium urealyticum).

Corynebacterium group D2 inoculated into normal human urine formed struvite crystals and an increase in pH and ammonium concentration after 24 h of incubation. Zinc disks dipped into a broth culture of this microorganism and inserted into the bladders of rats produced stones with a mean weight of 12.5 mg (ranging from 1 to 57.7 mg) after 12 days. Analysis of the infrared spectrum determined the stones to be composed of struvite. From these results its seems that stone formation by Corynebacterium group D2 may be possible both in vitro and in vivo, which may confirm a previous report involving these bacteria in human clinical encrusted cystitis.