Urinary Tract Infection (UTI) is a very common disease. It can present with cloudy urine, urine with sediment or even clear urine. What if the urine is purple in colour? Is it an alarming colour? We would like to highlight our purple encounter - purple urine bag syndrome (PUBS).
A 66 year-old female bed bound woman presented to a district hospital with difficulty in passing urine. Her bladder was catheterised, noted hematuria thus irrigation was performed. Post bladder irrigation, her urine was clear for 3 days. Her condition deteriorated and was referred to us for further management. Upon arrival, she was tachypneic and dehydrated.Temperature = 37.5 ◦C, pulse rate = 146 beats per minute, blood pressure = 123/66mmHg, SpO2 = 95%. Systemic review was unremarkable. Her urine bag was filled with purple-coloured urine. Urine analysis showed pH 9, Leukocytes=3+, Ketone=4+, erythrocytes=4+ and nitrate negative. Total white count = 26.7x109/uL. Urosepsis was diagnosed and she was treated with intravenous cefuroxime and admitted for further care.
PUBS is a rare entity. It is characterised by a purple discolouration of the urine bag in patients with prolonged bladder catheterisation in occurrence of UTI. The pathogenesis of it is the metabolism of dietary tryptophan by intestinal bacterias. The metabolites are catalysed by bacteria producing sulfatase and phosphatase into indirubin (red) and indigo (blue) pigments in the presence of alkaline urine. These pigments interact with the plastic of the urine bag to create the purple colour. It generally affects female with profound disabilities on long term bladder catheterisation. It can be thought that it requires the presence of all the above factors to develop PUBS. Therefore, it is an uncommon encounter.
The purple-coloured urine can be distracting but PUBS is generally benign. Treatment should be aimed at the underlying infection and catheterisation hygiene.