A Case Report: An Unusual Presentation of Purple Urinary Bag Syndrome

Abstract

Background: The Purple Urinary Bag Syndrome (PUBS) is an uncommon and under-reported syndrome. It results from the purple discoloration of urine by tryptophan-oxidizing bacteria in a favorable alkaline milieu and usually affects patients with indwelling catheters. Other risk factors include female gender, chronic constipation, tryptophan-rich diet, and cognitive impairment. Although asymptomatic in the majority of cases, PUBS may be the sole and earliest sign of an aggressive urinary tract infection, especially in elderly patients where the presentation may be atypical and associated with resistant organisms, such as Pseudomonas aeruginosa and Vancomycin-resistant Enterococci (VRE). Proper treatment consists of catheter replacement and antibiotic therapy, which is indicated only in the setting of symptomatic infections.

Case Presentation: We report an unusual presentation of PUBS in a 79-year-old male patient with no classical risk factors. The patient had a supra-pubic catheter for urinary retention secondary to urethral strictures. Every month, by the time of catheter exchange, the patient developed an asymptomatic purple discoloration of the urinary bag, which was not investigated until he presented at our facility. Urine analysis revealed acidic urine. Appropriate antibiotic therapy was initiated after the development of urinary symptoms, and the catheter was replaced. No recurrent urine discoloration occurred.

Conclusion: This case represents the rare occurrence of PUBS in the setting of a suprapubic catheter in a male patient. It also highlights that even in atypical presentations, antibiotic therapy should be tailored to the clinical status of the patient and not the mere presence of bacteriuria. Raising awareness about this “esoteric” syndrome is essential for early diagnosis and proper management.