Successful Treatment of Renal Abscess with Percutaneous Needle Aspiration in a Diabetic Patient with End Stage Renal Disease Undergoing Hemodialysis

Abstract

Renal abscesses in patients with end stage renal disease are quite rare, and misdiagnosis or delaying in diagnosis is frequent. This report examines a case of renal abscess in a patient with end stage renal disease on maintenance hemodialysis and diabetes mellitus, which presented with a prolonged fever. An infected diabetic foot was impressed initially. Purulent urine, pyuria, bacteriuria, and bacteremia were noted after admission. Renal abscess was diagnosed by percutaneous needle aspiration under computerized tomography guidance. The patient was treated with parenteral antibiotics and percutaneous aspiration of the abscess. Follow-up ultrasonography showed renal abscess resolution. This case demonstrated that nephrectomy was not required in selected uremic patients with renal abscess.

• Chronic renal failure
• Dialysis
• Urinary tract infection
• Renal abscess

Introduction

Renal abscess is uncommon; its onset and clinical course are insidious, its symptoms are highly variable, and unrecognized and untreated, it results in considerable morbidity and mortality.[[1]], [[2]], [[3]], [[4]], [[5]] The diagnosis of renal abscess in patients with end stage renal disease (ESRD) is frequently delayed because the urine-deprived urinary tracts are ignored as potential infection sites.[[6]] Renal abscess treatment in ESRD patients frequently requires nephrectomy.[[6]], [[7]], [[8]] This report investigates a diabetic patient with ESRD on maintenance hemodialysis, which had a renal abscess and was successfully treated with percutaneous aspiration and parenteral antibiotics.

Case Report

A 65-year-old female patient was admitted to our hospital with a 2-day fever as her chief complaint. She had been on hemodialysis for three years for her ESRD, and was anuric with a urinary amount of a few milliliters per day. The underlying etiology of ESRD was diabetic nephropathy. She also had a 24-year history of type 2 Diabetes Mellitus (DM) with insulin control, and an 8-year history of hypertension with medical treatment. The patient had in fact been admitted to our hospital twice for an infected left diabetic foot, 3 and 2 months prior to the current admission. Wound cultures during previous admission yielded Staphylococcus aureus. There were no symptoms of dysuria, urinary frequency, urinary urgency, nausea, vomiting, or flank pain prior to her current admission; her body weight was 90 kg and height 152 cm. Blood pressure was 103/85 mmHg, pulse rate 91/min, respiratory rate 18/min, and body temperature 38.9°C. Physical examination showed a small wound associated with surrounding erythematous swelling, and local heat at the left fifth toe. There was no tenderness at the costovertebral angle. Laboratory data showed hemoglobin 10.9 gm/dL, WBC 9400/mm³, segment 89%, Band 2%, monocyte 2%, and lymphocyte 7%. Blood chemistry tests showed creatinine 8.1 mg/dL and Ac sugar 394 mg/dL. The left diabetic foot was treated with cefazolin and gentamicin for a suspected infection. Dark red purulent urine was noted on the second hospitalization day. Urinalysis displayed 12–14 red blood cells per high power field, protein 500 mg/dL, and >100 white blood cells per high power field. Blood cultures and a urine culture yielded E. Coli, sensitive to gentamycin, amikacin, aztreonam, and ceftriaxone. The fever persisted despite improvement of the erythematous swelling of the left foot. A renal echo revealed a 4.8 cm hypoechoic renal mass with an irregular wall, and abdominal computerized tomography (CT) showed a 5.0 cm low-attenuation mass, both at the right kidney's lower pole (Fig. 1). Percutaneous needle aspiration and biopsy under CT guidance were performed on the 15th hospitalization day. Aspiration yielded 15 cc of dark red purulent material. Percutaneous drainage was not performed due to the small amount of pus. Septic shock immediately developed after the procedure, and the antibiotic regimen was changed to ceftriaxone and gentamycin. The hemodynamic stabilized the following day. The biopsy result was negative for malignancy. An aspirate culture yielded E. coli with the same sensitivity as the previous blood and urine cultures. The antibiotic regimen was changed to amikacin on the 22nd hospitalization day because of the persistent fever, which later subsided. The patient was discharged on the 31st hospitalization day and had an uneventful followed-up at the outpatient department.

Figure 1. CT scan showing a low-attenuation mass with an irregular wall (arrow) in the right kidney's lower pole.

Discussion

Uremic patients have compromised immune systems and an increased infection frequency. Infection is a major cause of mortality and morbidity in hemodialysis patients.[[9]] The incidence of urinary tract infections in ESRD patients ranges from 0.2 to 1.1 episodes per 100 patient-months.[[10]] Azotemia, infrequent voiding, low urinary flow rates, and urinary concentration defects have all been reported as leading to bacteriuria.[[11]] Urinary tract infections were in fact the second most important source of bacteremia, with gram-negative bacilli, mainly E. coli, almost always being the causative microorganisms.[[5]], [[12]]

Renal abscess is uncommon, with major risk factors including renal stones, urinary tract obstruction, and DM.[[2]], [[3]], [[4]], [[7]], [[13]] Enteric aerobic gram-negative bacilli, including E. coli, Klebsiella species, and Proteus species are commonly responsible for this infection.[[4]], [[5]], [[7]], [[14]] The risks of urinary tract infection and renal abscess increased in the current report's patient since she had DM and had been anuric.

The symptoms of urinary tract infections in ESRD patients are no different to patients without renal failure, except a greater frequency of gross hematuria.[[12]] As the presenting symptoms are vague and nonspecific, a delay of weeks or months may occur before a renal abscess diagnosis is made.[[1]], [[2]], [[3]], [[4]], [[5]], [[6]], [[7]], [[8]] The typical renal abscess presentation includes fever, chills, and flank or abdominal pain. Dysuria is not necessarily present, although leukocytosis is generally present and the urinalysis is often abnormal with bacteriuria, pyuria, proteinuria, or hematuria. Bacteremia is frequently present in renal abscess patients.[[1]], [[2]], [[3]], [[4]], [[5]], [[7]]

Computerized tomography and ultrasonography are used to establish a renal abscess diagnosis. Fowler et al. reported that ultrasonography and CT identified 92% and 96% of abscesses, respectively.[[4]] CT scan findings commonly include a soft tissue mass of central attenuation, an inflammatory wall with a slightly higher attenuation coefficient on unenhanced views, a ring sign (a ring of increased density in the abscess wall after injection of contrast material), obliteration of surrounding tissue planes, ipsilateral enlargement of the kidney or psoas muscle, thickening of Gerota's fascia and gas or air fluid level within the lesion.[[14]] These signs are not specific for renal abscess, and the ring sign could not be demonstrated in the current report's patient, because of renal dysfunction. Percutaneous needle aspiration should be performed under sonographic or CT guidance to make a definite diagnosis.

The choice of antibiotics for treatment of urinary tract infections in ESRD patients is complicated, and the efficacy of many of these drugs depends on the concentration achieved in the urine. Patients with reduced renal excretory function or oligoria may be unable to achieve an adequate urine or tissue drug level. Ampicillin, trimethoprim-sulfamethoxazole, cephalosporin, semisynthetic penicillin, and aminoglycoside have been used previously.[[12]], [[15]] Renal abscess treatment includes medical therapy, percutaneous aspiration, and surgery.[[1]], [[2]], [[3]], [[4]], [[5]], [[7]], [[16]] Small abscesses (less than 3 cm) in immunocompetent patients can be treated with antibiotics alone,[[13]], [[16]] although larger abscesses (greater than 3 cm) require percutaneous drainage or surgery. Treatment of renal abscesses in patients with renal dysfunction is more complicated, and nephrectomy is required.[[6]], [[7]], [[8]] Mortality of these patients is high—3 of 5 patients with polycystic kidney disease undergoing hemodialysis died in a previous report.[[8]] The current study's patient with DM and ESRD on maintenance hemodialysis had a renal abscess, and was successfully treated with antibiotics and percutaneous aspiration alone.

In conclusion, although renal abscesses in ESRD patients are rare, the possibility should never be excluded when making a diagnosis. Because the urinary tract is nonfunctional, it is often disregarded as a potential infection site. The most important step in renal abscess diagnosis is to remember that the condition exists. Nephrectomy may be unnecessarily in certain patients who responded to medical therapy and abscess aspiration.