A case of MPO-ANCA-associated vasculitis due to prosthetic knee infection with Staphylococcus aureus

Abstract

A 72-year-old woman with a history of left nephrectomy due to renal cell carcinoma, was administered antibiotics to treat a Staphylococcus aureus infection of a prosthetic knee. Rapid-progressive renal failure developed with oligouria during the antibiotic regimen and a laboratory examination demonstrated hematoproteinuria and increased levels of serum myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA). Gallium scintigraphy demonstrated increased uptake in the right kidney and in the right knee joint. MPO-ANCA-associated vasculitis and interstitial nephritis were suspected. Prednisolone therapy was administered with a reduced dose (0.4mg/kg/day) considering that the infection had already started, but this did not improve renal function and both sensorineural hearing loss and encephalopathy subsequently occurred. Plasma exchange by transfusion with fresh-frozen plasma (40 units) was performed and steroid pulse therapy (methyl prednisolone 500mg/day for three days) was followed by prednisolone 0.5mg/kg/day that was tapered every two weeks. This strategy improved the neurological symptoms and renal function. Plasma exchange combined with a lower dose of steroid was effective without aggravating a complicating infection in a patient with MPO-ANCA-associated vasculitis.