How did this happen? BD
Over the next 3 days, the urine gradually became yellow and clear, in the absence of antibiotic treatment. Purple discoloration can occur in alkaline urine as a result of the degradation of indoxyl sulfate (indican), a metabolite of dietary tryptophan, into indigo (which is blue) and indirubin (which is red) by bacteria such as Providencia stuartii, Klebsiella pneumoniae, P. aeruginosa, Escherichia coli, and enterococcus species.
Hat Tip: Kevin, MD