Purple Urine Bag Syndrome (PUBS) in a Bedbound Nursing Home Resident: A Rare Presentation of Urosepsis in an Elderly Patient

Introduction:

Purple urine bag syndrome is an uncommon but visually striking finding in catheterised patients, particularly those who are elderly, constipated, or in long-term care. It results from bacterial metabolism of dietary tryptophan, leading to pigment formation within the urinary catheter system. Although often benign, it can be an indicator of underlying infection or evolving sepsis.

Case Presentation:
A seventy-five-year-old male resident of a nursing home was admitted following concerns of fever, hypotension, and reduced consciousness. On arrival, he had a Glasgow Coma Scale score of 9/15 (baseline 12/15), with purple-coloured urine visible in his long-term suprapubic catheter system. His past medical history included dementia, multiple sclerosis, epilepsy, hypothyroidism, heart failure, stroke, and bladder stones. Laboratory investigations revealed a raised C-reactive protein of 59 milligrams per litre and a white cell count of 10.4 with neutrophilia. Chest imaging was unremarkable. Empirical antibiotic therapy was initiated, and the catheter system was replaced. Although urine culture was obtained after antibiotic administration due to clinical urgency, it later grew mixed organisms. The patient’s clinical condition and urine colour normalised, and he was safely discharged to his usual residence.

Discussion:
Purple urine bag syndrome was first formally reported in 1978. The condition is believed to affect fewer than ten percent of elderly patients with long-term catheterisation. It results from gut bacterial metabolism of tryptophan into indoxyl sulphate, which is converted by urinary bacteria into indigo and indirubin pigments. Risk factors include advanced age, chronic constipation, female sex, alkaline urine, and indwelling catheters.

Key Learning Points:

• Purple urine bag syndrome can be a visual marker of urinary tract infection or evolving sepsis.
• Recognition is important in frail, catheterised patients with multiple comorbidities.
• Management includes antibiotics, catheter change, and addressing predisposing factors such as constipation and dehydration.