What is the cause of Purple Urine Bag Syndrome (PUBS)?

From the Guidelines

Purple urine bag syndrome should be managed by changing the catheter, improving catheter care, and administering appropriate antibiotics based on urine culture results, as the condition indicates an underlying urinary tract infection that requires attention. This condition is a rare phenomenon where the urine in a catheter bag turns purple due to specific bacterial infections in patients with long-term urinary catheters, such as Providencia, Klebsiella, Proteus, Escherichia coli, or Pseudomonas, which convert dietary tryptophan into indigo and indirubin pigments, combining to create the purple color 1. The treatment approach involves addressing the underlying infection, and while the visually alarming condition itself is generally benign, it necessitates prompt medical evaluation.

Key Considerations

• The condition is associated with risk factors including female gender, constipation, alkaline urine, high bacterial load, renal dysfunction, and prolonged catheterization.
• Proper catheter management, such as regular changes every 2-4 weeks and adherence to good hygiene practices, is crucial in preventing purple urine bag syndrome.
• Patients and caregivers should be educated about this phenomenon to reduce unnecessary anxiety if it occurs, emphasizing the importance of monitoring for signs of urinary tract infection.
• Antibiotic treatment, typically with fluoroquinolones or third-generation cephalosporins for 7-10 days, should be guided by urine culture results to ensure effective management of the underlying infection 1.

Prevention and Management

• Regular catheter changes and meticulous catheter care can help mitigate the risk of developing purple urine bag syndrome.
• Educating patients and caregivers about the signs of urinary tract infection and the importance of seeking medical attention if such symptoms arise is vital.
• The use of antimicrobials in the drainage bag has not been shown to significantly reduce the risk of catheter-associated bacteriuria, as evidenced by studies such as those cited in 1, highlighting the need for alternative preventive strategies.

From the Research

Definition and Causes of Purple Urine Bag Syndrome

• Purple urine bag syndrome is an uncommon condition that occurs in patients with long-standing indwelling urinary catheters, due to urinary tract infection (UTI) by bacteria producing sulfatase or phosphatase enzymes 2, 3, 4, 5.
• The purple color of the urine is due to the formation of the pigments indigo (blue) and indirubin (red), which are metabolic products of biochemical reactions formed by bacterial enzymes in the urine 3, 4.

Risk Factors and Patient Characteristics

• Risk factors for purple urine bag syndrome include female gender, immobility, constipation, chronic catheterisation, and renal disease 3.
• The syndrome can occur in patients of various ages, including those in their 30s, 50s, and 70s 2.
• Patients with underlying medical conditions, such as non-Hodgkin's lymphoma, complete spinal cord compression, and cerebrovascular accident (CVA), may be more susceptible to developing purple urine bag syndrome 4, 5.

Management and Treatment

• Management of purple urine bag syndrome includes a change of catheter and appropriate antibiotics 2, 3, 6, 4, 5.
• Patient and caregiver education on proper catheter care is also important for prevention 2.
• In some cases, the purple color may disappear after changing the catheter and urinary bag, without the need for antibiotic treatment 4.

Prognosis and Complications

• The prognosis for patients with purple urine bag syndrome is usually favourable, but rare incidences of complications like Fournier's gangrene have been reported 2.
• The syndrome is associated with high morbidity and mortality due to the underlying medical conditions of the patients 3.