(P18) Purple Pee, Should We Worry

Introduction: The striking purple urine in the urine bag and tubing also known as “purple urine bag syndrome” (PUBS) is a rare disorder seen in elderly patients with chronic urinary catheters in place. The purple color is due to the buildup of indigo and indirubin in the urine, the end products of tryptophan metabolism by sulfatase and phosphatase produced by certain bacteria. PUBS is a usually a benign entity which may imply the possibility of a urinary tract infection (UTI) or suggest colonization of the urinary tract.

Case Description: The patient is a 54-year-old resident of a long-term care facility. He has an underlying history of multiple sclerosis, kidney stones and neurogenic bladder due to multiple sclerosis. He had an ileovesicostomy for bladder augmentation in 2001 with revision in 2011. He also has a diverting colostomy and a chronic indwelling foley catheter. He has had several admissions to the hospital for UTIs and prior history of long term suppressive antibiotic therapy alternating between ciprofloxacin and sulfamethoxazole/trimethoprim every 3 months. When he starts to develop an infection, the urine tends to change color. Urine cultures at the times of infection have shown Enterococci and Morganella. Sometimes changing the urinary catheter and bag has been sufficient to eradicate the infection.

Discussion: An estimated 2.8 million antibiotic resistant infections occur annually in the US according to the CDC with about 35,000 deaths per year. UTIs account for an estimated 1.6-2.18 billion dollars in health care costs each year which can be scaled down with antibiotic stewardship.
The patients with PUBS are usually asymptomatic. The purple color can sometimes be the telltale sign of a UTI.

Patients with PUBS have a chronic foley in place. Other risk factors include old age, female gender (short urethra with increased risk of UTI), alkaline urine, constipation (bacterial overgrowth in the colon which increases the conversion of tryptophan into indole), chronic renal insufficiency (reduced clearance of the tryptophan metabolites) and the use of plastic urinary catheters.
The bacteria involved are E coli, Providencia, Citrobacter, Enterobacter, Klebsiella, Morganella, Proteus and Streptococcus.

Bacterial sulfatase and phosphatase attach to the surface of the urine bag and oxidize indoxyl sulfate to indigo and indirubin, forming amorphous purple crystals on the surface of the bag.

Sometimes changing the urinary catheter and bag along with management of risk factors such as constipation, maybe sufficient for the treatment. Symptomatic UTIs should be treated with antibiotics tailored to the culture and sensitivity of the urine. Patients usually do not have any complications with timely and appropriate treatment.

PUBS is a rare, though anxiety provoking condition for staff and families, seen in residents of long-term care institutions and being aware of PUBS by the geriatrician can avoid unnecessary work up and treatment.