Purple Urine Bag Syndrome

Purple Urine Bag Syndrome, abbreviated to PUBS, is a somewhat uncommon medical syndrome where purple discolouration of urine occurs in people with urinary catheters and co-existent urinary tract infection. Bacteria in the urine produce the enzyme indoxyl phosphatase. This converts indoxyl sulfate in the urine into the red and blue colored compounds indirubin and indigo[1].

The most commonly implicated bacteria are Providencia stuartii, Providencia rettgeri, Klebsiella pneumoniae, Proteus mirabilis, Escherichia coli, Morganella morganii, and Pseudomonas aeruginosa.

People that display Purple Urine Bag Syndrome usually do not complain of any symptoms. Purple discolouration of a urine bag is often the only symptom, frequently first noted by caregivers. It is usually considered a benign condition, although in the setting of recurrent or chronic urinary tract infection, it may be associated with drug-resistant bacteria.

Antibiotics such as ciprofloxacin should be administered and the catheter should be replaced. If constipation is present, this should also be treated.

Purple Urine Bag Syndrome is more common in female nursing home residents. Other risk factors include alkaline urine, constipation, and polyvinyl chloride catheter use.

[1] Sabanis et al: Purple Urine Bag Syndrome: More Than Eyes Can See in Current Urology – 2019. See here.