[An experimental study of infection stone formation by Corynebacterium species]

The relationship between infection stone and Corynebacterium species was investigated in vitro and in vivo. Urease activity of urease-splitting Corynebacterium species was evaluated by 2 methods; an increase in pH of human urine after inoculation of Corynebacterium species and direct measurement of urease activity of 10(7) CFU organisms from amounts of ammonia by indophenol method. Formation of infection bladder stone was induced in male Wistar rats by implanting a zinc disc and inoculating 10(6) CFU organisms surgically into the bladder. Urine was alkalinized by the inoculation of Corynebacterium renale, C. pilosum and group D2 Corynebacterium. C. renale and C. pilosum had strong urease activity, and group D2 Corynebacterium had moderate activity. C. pseudodiphtheriticum did not produce the elevation of urinary pH and had little urease activity. Infection stones were formed in 100% of rats by inoculation of C. renale and C. pilosum and 88% of rats by group D2. Urinary pH was elevated in all inoculated rats. In conclusion, C. renale, C. pilosum and group D2 Corynebacterium may play a role in formation of infection stones.