Purple Urinary Bag Syndrome in a Patient with Acidic Urine: A Case Report

Authors

Keywords:

indwelling urinary catheter, pigmentation disorders, Bacteria Urinary Tract Infections, Bacteriuria, Purple urine bag, Purple urine, Case Report, urinary catheters, Urinary tract infection (UTI), Catheter-Related Infection, Urine, Proteus mirabilis

Abstract

Background:
Purple urine bag syndrome (PUBS) is an uncommon condition characterized by a purple discoloration of urinary drainage systems. This phenomenon results from bacterial metabolism of tryptophan derivatives into indigo and indirubin pigments. PUBS predominantly occurs in elderly, chronically catheterized female patients with alkaline urine and constipation. Reports of PUBS in patients without these classical risk factors remain exceedingly rare.

Case:
A 76-year-old male from El Salvador with a medical history of hypertension, atrial fibrillation, benign prostatic hyperplasia, and long-term urinary catheterization presented for routine catheter replacement. He reported a 15-month history of recurrent purple discoloration of the urine bag associated with dysuria and suprapubic pain, but denied fever, flank pain, or constipation. Physical examination revealed suprapubic tenderness and characteristic purple discoloration of the drainage system. Laboratory studies showed normal renal function and acidic urine (pH 6). Urine culture grew extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis, sensitive to trimethoprim/sulfamethoxazole. Empiric ciprofloxacin therapy was initiated and subsequently adjusted to targeted antibiotic treatment, resulting in complete resolution of symptoms and discoloration. Follow-up urine analysis and culture were negative.

Conclusions:

This case illustrates an atypical presentation of PUBS in a male patient with acidic urine and absence of the conventional risk factors. Awareness of PUBS as a benign yet clinically relevant indicator of urinary tract infection is crucial. To our knowledge, this represents the first documented case of PUBS in El Salvador, broadening the recognized epidemiological and clinical spectrum of this syndrome

Author Biographies

Paolo Vigne, Universidad Dr José Matías Delgado

Paolo Vigne, MD, graduated from the Universidad Dr. José Matías Delgado, La Libertad, El Salvador, in May 2025 from an eight-year medical program. He is a recipient of the Diploma de Honor al Mérito for achieving first place in the poster presentation “Vectores Adenovirales como nueva alternativa en el tratamiento de la enfermedad de Pompe infantil” at the Eleventh Annual Poster Research Competition of the Faculty of Health Sciences “Dr. Luis Edmundo Vásquez.” He has also passed the USMLE Step 1 examination and has authored multiple publications indexed on Google Scholar.

Rodrigo Aparicio, MD. Universidad Dr. José Matías Delgado, La Libertad, El Salvador

Rodrigo Aparicio, MD, graduated from the Universidad Dr. José Matías Delgado, La Libertad, El Salvador, in May 2025 from an eight-year medical program. He is currently pursuing postgraduate studies in Emergency Medicine in El Salvador and working at the Instituto Salvadoreño del Seguro Social (ISSS). Dr. Aparicio is also an active member of the Salvadoran Red Cross, where he continues to develop his commitment to prehospital and humanitarian medicine. He holds certifications in Advanced Cardiovascular Life Support (ACLS) by the Emergency and Care Safety Institute, and in Prehospital Trauma Life Support (PHTLS) and Advanced Medical Life Support (AMLS) by the National Association of Emergency Medical Technicians (NAEMT). He also completed a Diploma in Clinical Electrocardiography endorsed by the Emergency Medicine Association of El Salvador.

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Published

2026-06-25

How to Cite

Vigne, P., & Aparicio, R. (2026). Purple Urinary Bag Syndrome in a Patient with Acidic Urine: A Case Report. International Journal of Medical Students. Retrieved from https://ijms.info/IJMS/article/view/4166

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