Purple Urine Bag Syndrome (PUBS) is an uncommon condition characterized by purple discolouration of urine secondary to urinary tract infection (UTI) induced by chemical reactions. It is easily reversible by eliminating the causal organisms. This report highlights an elderly woman presenting with alarming urinary discoloration.
Background
This report aims to make healthcare personnel aware of the alarming through rare presentation of UTI which is very common in daily clinical practice, so that misdiagnosis and unnecessary measures can be avoided. At the same time, effective treatment of this condition can promptly be commenced.
Case Presentation
A 59-year-old-woman with hypertension, recurrent ischemic strokes, Type 2 Diabetes Mellitus on regular medications and renal stones on conservative treatment presented with purple discolouration of urine. She had been bed-ridden and had became feeding tube and urinary catheter-dependent since a second cerebrovascular accident (CVA) in 2021. Nursing care including tube and catheter care had been performed by a family member. A day after re-catheterization, the care giver noticed dark purple coloured urine so they rushed her to the hospital. On symptom review, she denied fever, dysuria, back pain and other systemic symptoms, apart from constipation for three days. Her urine output was not reduced.
On admission, her GCS was 13/15 (E-4, V-4, M-5) with no dyspnea , no orthopnoea. Vitals were stable (BP 140/90 mmHg, HR 80/min, SPO2 96% on air). Apart from left hemiparesis, there was no other sign on systemic examination. However, urine colour was typically changed to dark purple as in the following figure.
Fig 1-A urinary catheter and a collection bag showing purple discolouration
Investigation and Treatment
Empirical parenteral broad spectrum antimicrobial therapy (Levofloxacin) was given after taking blood and urinary samples. Urinalysis showed a pH 6.0, Nitrite +, Leucocytes 3+ , Blood 1+ , Protein 2+ , glucose negative, with white cell count 754.4/HPF, red cell count 10.9/HPF and Bacteria 1850/HPF. Blood tests revealed mild neutrophil leucocytosis and marginally raised CRP (6.28 mg/L). Urine culture turned out to have a heavy growth of Citrobacterkoseri sensitive to cephalosporin, carbapenem and fluoroquinolone groups, fortunately with the best MIC with fluoroquinolone class (MIC _< 0.06).And other blood parameters such as serum creatinine, electrolytes, liver function tests and thyroid function tests were within normal ranges.
Outcome
On third day of antibiotics, her urine color returned to normal. IV antibiotic was given for 5 days and then she was safely discharged.
Fig 2 –normal urine color on 3rdday of IV antibiotics
Discussion
PUBS was first reported in 1978 in The Lancet.1
The pathogenesis of purple urine bag syndrome is due to the metabolism of tryptophan by bacteria to indole and later converted to indican in the liver. This is excreted and broken down in the urine by bacteria possessing one or both enzymes, sulphatase and phosphatase that metabolize this pigment to indirubin and indigo in an alkaline environment (urine).
Prolonged catherization and history of renal stones and glycosuria are important risk factors for developing purple urine syndrome.2
Microorganism causing PUBS3
Escherichia coli
Klebsiella pneumoniae
Proteus mirabilis
Pseudomonas aeruginosa
Providencia stuartii
Providencia rettgeri
Morganella morganii
Proteus vulgaris
Proteus penneri
Streptococcus agalactiae
Acinetobacter baumannii
Enterobacter cloacae
Klebsiella oxytoca
Staphylococcus epidermidis
Citrobater spp.
Gram-negative coliforms
The strong association with constipation and intestinal obstruction has been well described.4
Conclusion
PUBS is a rare presentation of urinary tract infection with an alarming appearance and can increase anxiety amongst patients and family members. It often occurs in chronically catheterized and constipated patients who have significant underlying comorbidities. Although relatively benign and easily treatable, it can be associated with significant morbidity and mortality. The treatment should be aimed at the underlying medical problem rather than purple bag itself.
References
1. Barlow GB, Dickson JAS (1978) “Purple urine bags”. Lancet 311:220–221.
2. Dealler SF, Hawkey PM, Millar MR. (1988) “Enzymatic degradation of urinary indoxyl sulfate by Providencia stuartii and Klebsiella pneumoniae causes the purple urine bag syndrome”. J Clin Microbiol.;26:2152–6.
3. Mantani N, Ochiai H, Imanishi N, et al. (2003) “A case-control study of purple urine bag syndrome in geriatric wards”. J Infect Chemother ; 9:53-7.
4. Harun NS, Nainar SK, Chong VH.(2007) “Purple urine bag syndrome: a rare and interesting phenomenon”. South Med J; 100:1048-50.
Author Information
Yan Lynn Aung, Phyu Phyu Lay
Department of Neurology, Yangon General Hospital, Myanmar
