Analysis of human urine for mutagens associated with carcinoma of the bilharzial bladder by the Ames Salmonella plate assay: Interpretation employing quantitation of viable lawn bacteria

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Abstract
The Ames Salmonella plate assay was employed to test urine samples from bladder cancer patients and controls living in Egypt for the presence of chemical mutagens. Urine from five groups of Egyptian adults were tested, including individuals with (1) neither bilharziasis nor bladder cancer, (2) urinary bilharziasis and normal urinary cytology, (3) urinary bilharziasis and atypical urinary cytology, (4) carcinoma of the bilharzial bladder, and (5) bladder cancer without bilharziasis. Plates treated with histidine dependent bacteria, S‐9 mix, beta‐glucuronidases and 0.3 ml sterile urine from all five groups yielded 50 to 150 percent more colonies than plates treated with saline instead of urine. These differences were highly statistically significant for all groups except subjects with bladder cancer without bilharziasis. Gross and microscopic inspection suggested, however, that plates containing urine had heavier bacterial lawns than plates treated with saline. A procedure for quantitating viable bacteria in the lawn was devised which demonstrated that the increase in colonies on urine treated plates could be attributed to increased numbers of viable bacteria in the bacterial lawn on those plates. There was, therefore, no convincing evidence for the presence of mutagenic substances in these urine samples.