Purple Urine Bag Syndrome: A visual diagnosis and what it means for your patient

A 78-year-old male is brought in from his nursing home for evaluation of hypotension. He has a prior history of multiple strokes and is bed bound. He arrives febrile, tachycardic, and hypotensive. On your physical exam, you notice that he has an indwelling foley catheter. The catheter tubing and bag have a vibrant purple color. You wonder if this unusual urine color could be caused by something insidious. Could this be related to a toxin, medication, or infection?