Bacteriology and composition of infected stones.

One hundred forty-two stones from 106 male and 36 female patients were investigated bacteriologically and chemically. Twenty (14%) of these stones were infected; 65 per cent were associated with infected urine. In 45 per cent of these infected stones an identical bacteria species was isolated from urine and stone of the same patient. Most of the infected stones were of the oxalate type (II), followed by uric acid/urate (5) and calcium phosphate (4) types. Only one stone grew a definite urea-splitting organism.