Emphysematous pyelonephritis due to mucormycosis

Case report

A 43-year old man presented with fever with chills and right flank pain of three days’ duration. On examination, he was febrile with tachycardia and right renal angle tenderness. Investigations revealed aleucocytosis: 15.4 × 10⁹/L, anaemia (Hb: 81 g/L), serum creatinine (82.3 μmol/L) and serum albumin (24 g/L), and urine microscopy showing 10–15 pus cells/hpf.

An abdominal ultrasound showed an enlarged right kidney (116 × 67 mm in size), heterogeneously hypoechoic in echotexture with evidence of air pockets in the interpolar region. There was no hydronephrosis or calculus, and the left kidney was 110 × 54 mm in size. An abdominal computed tomography scan showed evidence of acute emphysematous pyelonephritis (EPN) on the right mainly involving the medial and postero-inferior aspects with pararenal extension. Blood and urine cultures showed no growth.

Intravenous piperacillin tazobactam 4.5 g qds, metronidazole 500 mg bd and fluconazole 200 mg od were commenced. The placement of a double J stent was introduced as an emergency, but despite this, he continued feverish with right abdominal pain.

Antibiotic therapy was changed to intravenous imipenem cilastatin 500 mg bd after five days. A repeat abdominal ultrasound scan then showed large irregular-shaped hypoechoic collections with internal echoes in the right inguinal fossa, measuring 18 × 24 cm. These were drained through right retroperitoneal and perinephric percutaneous incisions.

Despite this, he continued to have abdominal pain, persistent sepsis with fever, leucocytosis at 32 × 10⁹/L and hypotension requiring inotropic support.

Therefore, after 10 days, an open right nephrectomy was carried out. The immediate post-operative period was stable, but on the second post-operative day, a wound site infection developed, which needed draining.

Renal histology showed spores and aseptate wide branching filamentous forms of fungi of Mucormycosis, reported as an EPN with florid fungal infection (Fig. 1). The edges of the surgical wound also showed the growth of Mucor.

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Figure 1.

Microscopic examination revealed broad aseptate fungal hyphae, gram stain 100× magnification under an oil immersion microscope.

Liposomal amphotericin B 3 mg/kg daily was administered for 14 days, on which treatment fever and abdominal pain finally subsided, with the closing of the surgical site wound.

Discussion

Our patient was not diabetic nor hypertensive with no obstructive uropathy. He was, however, a compulsive consumer of alcohol but had no past history of infection or hospitalisation. He should, however, be considered as immune-compromised.

Facultative anaerobes most commonly causing EPN are Escherichia coli (49% to 67%), Klebsiella (20% to 24%), Proteus (5% to 18%), Enterococcus (14%), and Pseudomonas (5%). ¹

Fungal aetiology has been reported in only a few patients, being due to Candida species, Aspergillosis and Cryptococcus, ² in patients with diabetes or an immuno-compromised status. Amoebiasis in a diabetic was found in another. ³ Some cases of EPN due to mucor have been reported;^4–6 details are shown in Supplemental Table 1.

Treatment should always begin with aggressive resuscitation, including adequate intravenous rehydration, oxygen, insulin-mediated euglycaemia, and broad-spectrum antibiotics. Early efficient drainage of abscesses is mandatory; this may well mean nephrectomy in an advanced case.

Supplemental Material