TUNBRIDGE M1,4, DAVIS H2, STEWART A3,4, JOHN G2,4
1Royal Adelaide Hospital, Adelaide, Australia, 2Department of Nephrology, Royal Brisbane and Women’s Hospital, Brisbane, Australia, 3Department of Pathology , Royal Brisbane and Women’s Hospital, Brisbane, Australia, 4University of Queensland, Brisbane, Australia
Background: Insect-sting induced minimal change disease (MCD) from bees and wasps (family Formicidae, order hymenoptera) has been reported. However, we report the first case of MCD associated with stings from an ant of the same order.
Case report: A 72-year-old female was referred to the nephrology service for oliguria and fluid overload 24 hours following uneventful Nissen fundoplication. 16 days earlier she experienced over a dozen stings from Myrmecia pilosula (Jack Jumper ants). A week later she developed swelling of both legs and 10 kg weight gain. She had history of hypertension.
The blood pressure was 178/83 mmHg, with elevated jugular venous pressure, anasarca and bibasal crepitations. Urine output was 300 mL/24 hours. Serum creatinine was 140 µmol/L (baseline 82 µmol/L). Urine microscopy revealed no erythrocytes, urine protein:creatinine ratio was 478, and albumin:creatinine ratio (uACR) 450. Serum albumin was 23 g/L, total cholesterol 4.8 mmol/L, and INR 1.0.
The renal histology including electron microscopy showed MCD. A trial of diuretic therapy failed with further fluid gain and rise in creatinine to 181 µmol/L. After a week prednisolone 75mg was commenced. At 1 month post-discharge, renal biochemistry had improved (creatinine 127 µmol/L, albumin 32 g/L, uACR 173). At 5 months renal function and weight returned to baseline (creatinine 87 µmol/L, albumin 34 g/L, uACR 0.5) and prednisolone was tapered off.
Conclusion: Jack jumper ants are native to Australia with allergic reactions up to 3%. Rather than a hypersensitivity reaction, MCD may result from either direct cytotoxic or charge-related effect of cationic venom peptides pilosulin 1-3 on anionic podocytes. Insect-sting associated MCD is usually steroid responsive with a good prognosis.
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