Purple urine bag syndrome: a unique clinical case and management considerations

Abstract

Purple urine bag syndrome (PUBS) is a rare and unusual event. It is related to symptomatic urinary infection and asymptomatic bacteriuria in patients with indwelling bladder catheters. The purple color of the urine is due to metabolic products of biochemical reactions formed by bacterial enzymes in the urine. Gastrointestinal tract flora breaks down the amino acid tryptophan into indole, which is subsequently absorbed into the portal circulation and converted into indoxyl sulfate. Indoxyl sulfate is then excreted into the urine, where it can be broken down into indoxyl if the appropriate alkaline environment and bacterial enzymes are present. The breakdown products, indigo, and indirubin appear blue and red. We reported on an elderly woman who was kept in a nursing home, had multiple comorbidities such as history of cerebrovascular accident (CVA), acute kidney injury (AKI) and she was hospitalized due to decreased consciousness, fever and kidney failure. On the third day of hospitalization, the patient developed PUBS while undergoing urinary catheterization in the hospital. She had no history of previous catheterization and chronic use of antibiotics, she was only using Tolterodine for a long time due to urinary urgency. Due to antibiotic resistance, the drugs were not changed and the purple color disappeared after changing the catheter and urinary bag.

This was the first patient in this region to be reported with this manifestation.

Introduction

Purple urine bag syndrome (PUBS) is a condition in which the urine drainage system turns purple due to a reaction involving tryptophan metabolism and certain bacteria [1]. It typically occurs in patients with long-term catheterization and a urinary tract infection (UTI), although this is not always the case [2]. While PUBS is usually considered harmless, it is crucial to assess each patient to check for an underlying UTI for those who may have difficulty expressing their symptoms, such as critically ill individuals or those with communication challenges [1, 2]. In this context, we present a case of an elderly woman with PUBS, which it appears to be the first documented occurrence of PUBS in this particular geographic region.

Case report presentation

A 73-year-old woman living in a nursing home with a history of old cerebrovascular accident (CVA) and deep vein thrombosis (DVT) on apixaban treatment was brought to Razi Hospital in Rasht (the city in the north of IRAN). She had decreased consciousness and she was febrile and arterial oxygen saturation (SaO2) was 88%.

During hospitalization, blood sugar was 123 mg/dL, blood pressure was 85/60 mm Hg, and after hydration and vasopressor treatment, it reached 140/80 mm Hg.

The patient was immediately intubated and dialyzed due to uremic encephalopathy with decreased levels of consciousness. Blood urea nitrogen (BUN): 160 mg/dL and creatinine (Cr):8 mg/dL. After blood and urine cultures due to fever and septic shock, Meropenem and Vancomycin were started with adjusted doses.

At the beginning of hospitalization, a urinary catheter was placed. The first day’s urine test included relative density: 1028; white blood count/high power field (WBC/HPF): 18–20; bacteria: Many; nitrite: Negative; pH: 5; and the result of Citrobacter urine culture with a colony count > 10⁵; which is only sensitive to nitrofurantoin and this antibiotic cannot be used with glomerular filtration rate (GFR) < 30 mL/min/1.73 m2.

Antimicrobial susceptibility testing showed sensitivity to Nitrofurantion and resistance to: Amikacin, Cefepime, Ceftriaxon, Ciprofluxasin, Co-trimoxazole, Gentamycin, Imipenem, Tazobactam. There was no change in antibiotics. The patient was dialyzed two times with an interval of one day, and Cr decreased to 4 mg/dL.

Three days later, although the patient had no history of long-term urinary catheterization, the urine color changed to purple (Fig. 1). Moreover, there was no history of chronic constipation in the patient.

Fig. 1

Purple discoloration of urine bag

Before this onset, we had no information about renal function and kidney size.

The patient had no history of taking antibiotics frequently, but she used Tolterodine.

continuously. She was taking Tolterodine for urge incontinence. She was a multiparous woman and probably had weakness of the pelvic floor muscles .

According to this issue, the urinary catheter was changed, and the urine test was rechecked, in the retest: relative density: 1018; pH: 7; WBC/HPF: 10_12; Bacteria: Many; Nitrite: Positive; and Klebsiella urine culture with a colony count > 10⁵ was resistant to all antibiotics even Nitrofurantoin.

Antimicrobial susceptibility testing showed resistance to: Nitrofurantoin, Amikacin, Cefepime, Ceftriaxon, Ciprofluxasin, Co-trimoxazole, Gentamycin, Imipenem, Tazobactam.

BUN: 38 mg/dL and Cr: 2.2 mg/dL. The patient’s complete blood count (CBC) examination showed: WBC: 12,500 cells/microL; hemoglobin (Hb): 8.3 g/dL; platelet (Plt): 117,000/microL. Blood culture growth was absent after 24 and 72 h, and even after a week. Twenty-four hours after replacing the urinary catheter; the color of the urine changed from purple to dark yellow (Fig. 2).

Fig. 2

Dark yellow urine 24 h after changing the urinary catheter and bag

Due to the lack of improvement in the level of consciousness with dialysis, neurology consultation and brain computed tomography (CT) scan were performed, the evidence was in favor of right middle cerebellar peduncles (MCP) infarction with hemorrhage.

Finally in addition to electrolyte correction treatment (sodium correction from 157 mEq/L to 141 mEq/L in 4 days) and several rounds of dialysis, antibiotic and neurological treatment, there was no improvement in the patient’s condition. Unfortunately, she died ten days after hospitalization.

Discussion

PUBS, a phenomenon that primarily affects patients with catheters, was initially documented by Barlow et al. in 1978. It is characterized by urine discoloration within the drainage bags, turning it purple [3]. Healthcare providers and researchers have long been intrigued by PUBS due to its appearance and association with UTIs and catheterization. Gaining an understanding of PUBS is crucial for patient care provisions.

Epidemiologically, urine discoloration primarily affects individuals who require long-term catheterization. Factors such as aging and comorbidities such as neurogenic bladder dysfunction increase susceptibility to this condition. Furthermore, gender differences were observed in the occurrence of this condition among individuals, with higher rates in females [4].

The literature review of past articles used data from a total of 87 patients. Within this group, 35 were male, 50 were female and there was no gender information for 2. The mean age of the patients was recorded to be 73.8 years [5].

In our case, there were multiple risk factors linked to PUBS, including aging, female gender, the utilization of a plastic urine bag [6].

Variations in the incidence of UTI-related urine discoloration across regions and institutions suggest that environmental factors, catheter care practices, and microbial flora may influence its prevalence [7].

The main factors behind the development of PUBS are primarily related to how bacteria in the gastrointestinal system break down tryptophan. This process produces a substance called indole, which then enters the bloodstream through the wall and travels to the liver. In the liver, indole transforms into indoxyl sulfate, eventually expelled from the body through urine. It is important to note that when someone has PUBS, bacteria in their catheter play a role in this process by converting indoxyl sulfate into pigmented compounds, such as indirubin and indigo. This microbial activity significantly contributes to urine discoloration that is characteristic of this syndrome [8, 9].

Diagnosing PUBS primarily involves identifying colored urine within drainage bags. However, it is essential to adopt an approach to determine its underlying cause effectively. Urinalysis plays a role in diagnosing PUBS by detecting pH levels, suggesting an alkaline urine environment conducive to the formation of indigo and indirubin. It is important to conduct urine culture and sensitivity tests to determine the pathogens responsible for the UTI, which helps confirm the diagnosis and aids in selecting appropriate antibiotics. Additionally, blood tests may be needed to evaluate reactions and identify any illnesses [10].

It is crucial to evaluate and perform laboratory investigations to rule out potential causes of urine discoloration, such as hematuria or the effects of certain medications. Clinical assessment is essential in identifying underlying tract abnormalities and UTIs. Recognizing these issues allows for an evaluation and timely administration of antibiotics, which can help prevent UTI progression and complications. When managing UTI-related urine discoloration, the focus should be on addressing the infection itself and optimizing catheter care. It is essential to use antibiotics that target bacteria-producing urease. Additionally, following catheter care practices, such as insertion, regular maintenance and timely changes can significantly reduce the risk of infection [11, 12].

After reviewing existing research, it was found that the common bacteria associated with PUBS are Providencia stuartii, Providencia rettgeri, Klebsiella pneumoniae, various Proteus species, Escherichia coli, Enterococcus species, Morganella morganii, and Pseudomonas aeruginosa.

Occasionally, there have been reports of Citrobacter spp, Staphylococcus spp, Streptococcus spp. in cases of Methicillin-resistant Staphylococcus aureus being linked to PUBS [8, 13, 14].

Recent studies suggest that PUBS is generally a condition that does not cause issues and often goes unnoticed. Therefore, experts recommend replacing the catheter and bag as the solution without resorting to antibiotics or extensive diagnostic procedures, such as urine cultures. These measures are typically reserved for patients with symptoms of underlying UTI. For individuals without symptoms, it is important to focus on treating the cause rather than just addressing the discoloration of the urine bag. In order to prevent PUBS recurrence, it is advisable to change drainage bags and using long-term indwelling catheters. Additionally, treating UTI-related urine discoloration usually leads to improvement within a day. This highlights the significance of monitoring symptoms and conducting urinalysis and urine cultures to track progress and evaluate treatment effectiveness [15, 16].

Conclusion

We should focus on advancements in catheter technology and care protocols to reduce catheter-related UTIs and improve outcomes for patients with PUBS. Collaborative efforts to establish databases can provide information for healthcare strategies and policies. Furthermore, conducting long-term studies that assess the impact of PUBS on outcomes and quality of life from a patient-centered perspective is crucial. In order to provide care for catheterized patients, it is essential to have an understanding of the causes, clinical presentation, management strategies, and epidemiology. The significant point in this case was having known risk factors, such as female gender, history of CVA and acute kidney injury (AKI). One unique aspect of this case report was the development of PUBS at the patient’s first catheterization, while the patient had no history of previous catheterization or antibiotic use. The urine was not alkaline. The presence of drug resistance, except for nitrofurantoin and the disappearance of PUBS without changing the antibiotic and only by changing the catheter, was noteworthy.

Further research and case reports will contribute to an understanding and improved outcomes for those affected by this condition.