Purple urine bag syndrome is a rare manifestation of bacteriuria on bladder catheter: case report

Background Purple urine bag syndrome (PUBS) is a complication of bacterial colonisation of bladder catheters in which urine turns purple in the tubing, as well as in the catheter bag. This rare phenomenon can be very worrisome and stressful for the patients and their families, as well as for the healthcare team taking care of them. Recognising this complication is essential in order to avoid misdiagnosis and erroneous treatment. We report a case of PUBS in a 71-year-old female patient. Case presentation A 71-year-old woman with previous medical history of schizophrenia was admitted to the emergency department for anorexia and suspicion of psychotic decompensation. Acute urine retention and rectal faecal impaction were clinically suspected and confirmed by bladder ultrasound and rectal examination, respectively. The patient underwent bladder catheterisation as well as a rectal enema. The day after her admission, our medical team was approached by the nurse in charge of the patient because of purple urine in her catheter bag and tubing. The diagnosis of PUBS was made with the help of the Oxford urine chart. A dipstick urinalysis revealed alkaline urine (pH = 8), and the urine culture was subsequently positive for Proteus mirabilis, which is sensitive to quinolones, beta-lactams and nitrofurantoin . The bladder catheter was changed. The patient received empiric antibiotic therapy with Levofloxacin 500 mg once daily. After obtaining the antibiogram, the targeted antibiotic therapy was adapted with oral Cefuroxime 500 mg three times a day for a total duration of seven days of antibiotic therapy. There was no recurrence of purple urine. Conclusion PUBS is a rare complication of bacteriuria, which induces a purple colouration of the tubing as well as the catheter bag. It is a simple spot diagnosis, as there is no other known cause of purple urine. This is why we believe that the Oxford urine chart represents a very interesting and easily accessible tool to help clinicians to investigate any abnormal urine colour.