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Volume: 12 Issue: 6 December 2014

FULL TEXT

CASE REPORT
Case Report of a Ureteral Obstruction by Candida Albicans Fungus Balls Detected by Magnetic Resonance Imaging in Kidney Transplant Recipient

In kidney transplant recipients, acute renal failure resulting from a ureteral obstruction by fungus balls is uncommon. We report a 60-year-old man diagnosed with ureteral obstruction caused by Candida albicans fungus balls early after transplant. Diagnosis was made by a T2-weighted magnetic resonance image, which demonstrated fungus balls as a low-intensity mass in the pelvis and microscopic examination findings in the urine. The patient was treated successfully with an antifungal agent and direct irrigation. It should be noted that fungus balls may cause ureteral obstruction of transplanted kidneys, possibly resulting in graft failure. Imaging of the kidneys and collecting system and aggressive debridement that adds to systemic therapy are necessary for early diagnosis and are central to a successful outcome.


Key words : Renal transplant, Infection, Acute renal failure

Introduction

In Japan, infection is a common cause of morbidity and mortality in renal transplant recipients receiving immunosuppressive agents more, and it is the main cause of death in these patients. Fungal infections may affect 5% to 20% of all solid-organ transplant recipients; the incidence may reach 5% in patients who have undergone a renal transplant.1,2 Although infections caused by Candida albicans are common in kidney transplant recipients, ureteral obstruction caused by fungus balls is rare. Early diagnosis is important, as ureteral obstruction may cause graft failure in these patients. Imaging and urine drainage to confirm graft function and obtain urine sample are keys to ascertain the cause of the obstruction. We report an case of ureteral obstruction caused by Candida albicans fungus balls within a deceased-donor renal transplant recipient.

Case Report

At Shimane University in Enya Izumo, Japan, in November 2010, a 60-year-old man received a kidney transplant from a 62-year-old male deceased donor. Immunoglobulin-A nephropathy was the cause of end-stage renal disease and before kidney transplant, the patient had been on dialysis for 13 years. The donor died from interstitial lung disease, and the kidney donation was performed after cardiac death was confirmed. The kidney transplant procedure was a standard technique and ureterovesical anastomosis was performed using the Lich-Gregoir technique without an indwelling double J stent. Cultures of the graft preservation fluid revealed no growth of bacteria or fungi. Initial immuno-suppression consisted of tacrolimus, mycophenolate mofetil, methylprednisolone, and basiliximab. The clinical course was uneventful. However, restoration of graft function was slow, and the patient required hemodialysis during the 3 weeks after transplant. He was discharged with a serum creatinine level of 229.8 μmol/L. The restoration speed and function of the graft were affected by long ischemic times (warm ischemic time, 18 min; cold ischemic time, 23 h).

Two months after the transplant, the patient showed decreased urine output and increased serum creatinine (491.5 μmol/L). Medications included tacrolimus 5 mg/day, mycophenolate mofetil 1000 mg/day, and methylprednisolone 4 mg/day, with trough tacrolimus level ranging from 6.1 nmol/L to 7.3 nmol/L. Physical examination findings at that time were normal, except for slight discomfort in the suprapubic area. Doppler ultrasound findings showed the graft hydronephrosis without vascular anomalies. Computed tomographic scanning could not specify the cause of the hydronephrosis of the graft kidney. A ureteroscopic examination was attempted, although we could not advance the scope to reach the obstruction; a percutaneous nephrostomy was performed. Antegrade pyelogram findings confirmed complete obstruction of the ureter, while the cause of the obstruction was unclear. Turbid urine was collected through the nephrostomy catheter, and a microscope smear showed Candida albicans (Figure 1). A T2-weighted magnetic resonance image was performed after placing the nephrostomy catheter, demonstrating a low-intensity mass in the pelvis, suggestive of fungus balls (Figure 2).

The patient was treated with oral fluconazole 25 mg/day, and local irrigation with amphotericin B in 50 mg/L of sterile water was performed intermittently once daily as an adjunct to systemic antifungal therapy. On the fourth day after beginning treatment, urinary output per urethra was increased, and urine through the nephrostomy tube was reduced. The nephrostomy tube remained in place for topical irrigation for 15 days; it then was removed after confirming that passage of the ureter was restored (Figure 3). At discharge, serum creatinine was 192.7 μmol/L and a urine culture was negative. At the time of this writing, at 24 months after discharge, the patient is doing well with a serum creatinine level of 130 μmol/L to 150 μmol/L. Urine cultures have remained negative, and ultrasound findings of the graft kidney demonstrate resolution of hydronephrosis with no arterial anomalies.

Discussion

Acute renal failure as a result of ureteral obstruction caused by fungus balls is uncommon and rarely reported in kidney transplant recipients.3-8 The cause of candiduria has not been well characterized in this patient population. Recently, Delgado and associates reported that the incidence of candiduria in renal transplant recipients in a 2-year period was 3.4%, which is similar to that among general hospitalized patients.9 Safdar and associates also showed that female sex, diabetes, neurogenic bladder, malnutrition, antibiotic use within 1 month before candiduria, presence of an indwelling catheter, and intensive care unit admission were risk factors for candiduria in renal transplant recipients.10 However, none of these factors was found in the present patient. We believe the long duration of dialysis and immunosuppressive agent administration may have influenced the immuno-compromised status, which led to candiduria.

Early diagnosis is the key to successful treatment of acute renal failure in kidney transplant recipients. Ureteral obstruction after transplant may be caused by several reasons other than fungus balls (eg, ureteral stones, ureteral tumors, ureteral stricture, pelvic abscess, and hematoma), which can be ruled out by imaging examinations. Although magnetic resonance imaging is not indispensable in cases with ureteral obstruction, it should be performed when other modalities fail to detect the cause of obstruction. Furthermore, a T2-weighted magnetic resonance image may be helpful for diagnosis in cases with fungus balls, as they are demonstrated as a low-intensity mass. Other than imaging studies, urine drainage is necessary to confirm graft function and acquire a urine sample for testing.

Asymptomatic candiduria in patients with a renal allograft does not need treatment. Nevertheless, imaging of the kidneys and collecting system is prudent to exclude the presence of an abscess, fungus balls, or urologic abnormality. The Infectious Disease Society of America guidelines recommend treatment of candiduria in kidney transplant recipients with oral fluconazole or amphotericin B for fluconazole-resistant organisms. Fungus balls can occur anywhere in the urinary collecting system, and aggressive surgical debridement should be performed, especially in kidney transplant patients, because those obstructing the urinary passage can damage graft function. Evidence regarding the effectiveness of injected antifungal agents into the urinary tract is questionable, although according to some reported cases, direct irrigation with amphotericin B has been effective.

Candida spp. may cause an infection of the bloodstream in transplant recipients, leading to sepsis.9 The present patient showed a rapid recovery from candiduria without developing dissemination candidiasis or pyelonephritis; thus, early diagnosis of ureteral obstruction and dissolution of the mechanical obstruction caused by the fungus balls were important for successful treatment. Additionally, topical irrigation and oral fluconazole were effective in this case to avoid sepsis and maintain graft function.

Ureteral obstruction caused by fungus balls is rare but should be considered in cases with hydro-nephrosis and acute renal failure. Imaging studies and microscopic examination of urine are keys to diagnosis. Magnetic resonance imaging was useful to detect the fungus balls in the present case. Early diagnosis, followed by treatment with systemic antifungal therapy and direct irrigation, may avoid infectious dissemination as well as graft failure.


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Volume : 12
Issue : 6
Pages : 559 - 561
DOI : 10.6002/ect.2013.0235


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From the Department of Urology, Shimane University, Enya Izumo, Japan
Acknowledgements: The authors have no conflicts of interest to disclose, and there was no funding for this study.
Corresponding author: Naoko Arichi, Department of Urology, Izumo Shimane University, 89-1 Enya Izumo 6938501 Japan
Phone: +81 853 202253
Fax: +81 853 202250
E-mail: naoko-a@med.shimane-u.ac.jp