Mutagenicity for Salmonella typhimurium of urine obtained from humans receiving nitrofurantoin.

Urine samples from 12 humans receiving oral therapeutic doses of nitrofurantoin were mutagenic for Salmonella typhimurium strain TA 100 and nonmutagenic for strain TA 100-FR1. Mutagenic activity of the urine was not increased by treatment with beta-glucuronidase. Spot mutation assay of the chromatogram of urine revealed that the mutagenic activity of the urine was mainly due to unmetabolized nitrofurantoin.