Purple urine bag syndrome with acidic urine - International Journal of ...

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pigments — indigo and indirubin — which dissolve in the plastic of the urine bag and result in the purple discoloration. PUBS is rare, but a prevalence as high as ...
International Journal of Infectious Diseases (2008) 12, 526—527

http://intl.elsevierhealth.com/journals/ijid

Purple urine bag syndrome with acidic urine Shiu-Dong Chung a, Chun-Hou Liao b, Hsu-Dong Sun c,* a

Division of Urology, Department of Surgery, Far Eastern Memorial Hospital, Ban Ciao, Taipei, Taiwan Division of Urology, Department of Surgery, Cardinal Tien Hospital, and College of Medicine, Fu-Jen Catholic University, Hsin-Chuang, Taipei, Taiwan c Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, 201, Shih-Pai Road, Section 2, Taipei 112, Taiwan b

Received 23 December 2007; received in revised form 12 February 2008; accepted 15 February 2008 Corresponding Editor: William Cameron, Ottawa, Canada

KEYWORDS Infection; Urinary bag; Bacteria

Summary Purple discoloration of a urinary catheter bag is very rare. This phenomenon is known as the purple urine bag syndrome. It is associated with urinary tract infections occurring in catheterized patients, generally elderly females with significant co-morbidities and constipation. The urine is usually alkaline. We present a unique case of this rare and interesting phenomenon occurring in acidic urine and discuss the pathophysiology. # 2008 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Introduction

Case report

Purple urine bag syndrome (PUBS) is a rare condition characterized by purple discoloration of urinary drainage bags. This clinical condition was first described in 19781 and was believed to be related to the metabolism of tryptophan.2 PUBS occurs predominantly in the elderly who are bedridden and have chronic urethral catheterization. This condition usually develops hours or days after catheterization and has been related to indicanuria and urinary tract infection caused by indicant (indoxyl sulfate) degrading bacteria.1,3,4 This syndrome is usually reported to occur in alkaline urine. We report herein a unique case of PUBS with acidic urine.

The case was an 85-year-old gentleman, paraplegic, with a past medical history of chronic kidney disease, old cerebral vascular accident, chronic constipation, hypertension, and the requirement for a chronic indwelling urinary catheter. The patient was being followed at our urology clinic for periodic replacement of the catheter. However, purple discoloration of his urine was noted (Figure 1). Reviewing his medications did not disclose any pharmacological agent that could cause urine discoloration. On physical examination, the patient was found to be afebrile, and some debris was found around the urethral meatus and within the catheter and drainage tube. Urinary analysis revealed a pH of 5.5, 50—80 white blood cells per highpower field, positive leukocyte esterase, positive nitrites, 10— 20 red blood cells per high-power field, and 1+ bacteria. Urine culture grew more than 100 000 colonies of Pseudomonas aeruginosa and Enterobacter cloacae. A diagnosis of complicated urinary tract infection was established; the patient was treated with 500 mg oral ciprofloxacin twice daily for 14 days. After receiving antibiotic treatment, his urine bag did not become purple again.

* Corresponding author. Tel.: +886 2 82419216; fax: +886 2 23219145. E-mail address: [email protected] (H.-D. Sun).

1201-9712/$32.00 # 2008 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijid.2008.02.012

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Purple urine bag syndrome with acidic urine

Figure 1 Purple discoloration of the urinary catheter plastic tube and bag.

Discussion The purple discoloration of urine drainage bags was first described by Barlow and Dickson in 1978. They linked the presence of indigo to the metabolism of tryptophan in the clinical setting of constipation, which undergoes bacterial decomposition to indoxyl sulfate.1 The chain reaction accounting for PUBS begins with tryptophan from food, which is metabolized by bacteria in the intestine. This metabolism will produce indole, which is absorbed into the portal circulation and is converted into indoxyl sulfate after a series of detoxification transformations in the liver. Indican is then excreted in the urine and metabolized into indoxyl by phosphatase/sulfatase produced from certain bacteria.2 Oxidation of free indoxyl in an alkaline urine will produce two main pigments — indigo and indirubin — which dissolve in the plastic of the urine bag and result in the purple discoloration. PUBS is rare, but a prevalence as high as 9.8% has been reported in patients in chronic care units.3 Stott et al. described three elderly female patients with PUBS, all of whom had alkaline urine, and concluded that the bacterial pathogens had no relation with the PUBS, and that indicanuria is not a prerequisite.5 PUBS has been associated with multiple pathogens, including Pseudomonas sp, Morganella sp, Proteus sp, Providencia sp, Klebsiella sp, and Enterobacter sp. 6 Gramnegative bacteria producing sulfatase and phosphatase are important in the pathogenesis.2,7 Dehydrated status or hypovolemia might also be important factors, as the serum concentration of indican, an important constituent, has been found to be correlated with advancing chronic kidney disease and azotemia. Several published works have demonstrated that the activity of bacterial indoxyl sulfatase, catalyzing the conversion of indican into indigo blue, is present only in strong alkaline urine.8,9 Lower serum levels of tryptophan and valine in patients with PUBS suggest abnormal absorption of amino acids secondary to constipation and intestinal bacterial overgrowth. A high tryptophan diet may increase the risk of developing this condition in susceptible patients. The presence of alkaline

urine is a common characteristic in most cases.10—13 In contrast, our case had PUBS in acidic urine. The pathogenesis of purple discoloration of the urine depends on bacterial colony counts and the concentration of indoxyl sulphate.9 Though discoloration will develop faster when the urine is alkaline, it is possible for this to occur in acidic urine.14 PUBS usually occurs in patients in geriatric wards and predominately affects females. There is no causative relationship between PUBS and bacteria strains, but bacterial counts are significantly higher in PUBS patients. This evidently increases the urinary pH, which will increase even more if an infection progresses.7 In the English literature, only one case of PUBS has been reported in acidic urine; our case is the second.14 Although uncommon, PUBS can also occur in acidic urine. The cause of PUBS has not been consistently proven, and it remains elusive. It has not been reported to have any implication other than the possibility of a urinary tract infection, and it has not been proven to have an impact on the outcomes of patients. The cases reported in the literature and our case demonstrate various important contributing factors to PUBS. Cases appear to be related to urinary tract infection, with their resolution shortly after antibiotic treatment. PUBS is a benign condition without major consequences.2,7 Clinicians dealing with patients who have indwelling bladder catheters need to be aware of this condition. Conflict of interest: No conflict of interest to declare.

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