Renal pathological findings in infective endocarditis

Background. Accounts of renal pathological findings in infective endocarditis are mostly based on studies from many years ago. We reviewed a group of patients with infective endocarditis in the light of modern concepts of renal pathology, including the largest reported series of renal biopsies in this condition. Methods. Renal tissue was available for retrospective study from 62 patients with confirmed infective endocarditis out of 354 diagnosed with the disease between 1981 and 1998 inclusive. Twenty patients had a renal biopsy and 42 a necropsy. Results. Common renal lesions noted were localized infarcts in 31%, noted only in necropsy material, and acute glomerulonephritis in 26%, noted in biopsy and necropsy material. The commonest type of glomerulonephritis was vasculitic, without deposition of immunoproteins in glomeruli. Of the renal infarcts over half were due to septic emboli, mostly in patients infected with Staphylococcus aureus. Acute interstitial nephritis was found in 10% but was more common in biopsy material and seemed attributable to antibiotics. Renal cortical necrosis found in 10% was apparent only at necropsy. There were various other findings in the kidney. Conclusions. The kidneys are commonly affected in infective endocarditis by a variety of complications of clinical significance. The commonest type of glomerulonephritis does not appear to be attributable to deposition of immune complexes. A renal biopsy may be helpful in the investigation of renal impairment in a patient with infective endocarditis.