Purple urine bag syndrome (PUBS) is an uncommon disorder, in which the plastic
disposable urinary catheter bag turns purple or blue following hours or days of urinary
catheterization. The purple discoloration results from indirubin dissolved in the plastic mixing
with indigo in the urine. Bacteria possessing indoxyl sulfatase degrade indoxyl sulfate into
indirubin and indigo. Indoxyl sulfate is derived from the metabolism of tryptophan. PUBS
usually occurs in chronic catheterized elderly women who are constipated and poorly …

A 72-year-old woman with end-stage diabetic nephropathy had been undergoing regular
hemodialysis for 3 years. She was bedridden after a cerebrovascular accident and had a
urinary catheter for residual urine drainage. On a certain occasion, a purple discoloration of
the urine and urine bag was noted (Figure 1). Urinalysis revealed pH 7.5, protein 3+,
numerous red blood cells, and white blood cells. Urine culture yielded Escherichia coli with
a colony count of more than 100,000 CFU per ml. Antibiogram of this isolate was consistent …