Urinary calculi: bacteriological and chemical association

We investigated the bacteriology of urinary calculi in relation to urinary tract infection, stone formation, chemical composition and antibiotic sensitivity. Fifty-two patients (37 males, 15 females) with urolithiasis were studied. Urine, serum and urinary calculi specimens were taken and serum biochemical tests to detect uric acid, calcium and phosphorus were performed. Urine analysis and culture were also performed. Of the 52 patients, 19 (37%) had associated urinary tract infection, with Escherichia coli and Proteus mirabilis being the most common causative microorganisms. The bacterial isolates from urine and those from calculi differed in their susceptibility to antimicrobial agents. We conclude that in over 50% of patients with urolithiasis, urine culture can detect the infecting organisms associated with stone formation and the organisms within urinary calculi.