Membranoproliferative glomerulonephritis complicating Propionibacterium acnes infection

BACKGROUND Propionibacterium acnes (P. acnes) is a common microbe of the skin and mucosal surfaces rarely considered a true pathogen. However, it has been reported to cause serious infections. Subsequent ongoing low-grade antigenaemia may, in turn, lead to an immune-mediated glomerulonephritis with various renal histologies including that of membranoproliferative glomerulonephritis (MPGN). METHODS Here, we describe two cases of P. acnes infection-induced MPGN and their treatment. RESULTS Both patients were successfully treated by the eradication of the infection. One patient also received immunosuppressive medication prior to the correct diagnosis. CONCLUSIONS A vigorous exclusion of infection is warranted in MPGN type I or immune-complex-mediated MPGN and may sometimes yield a diagnosis of secondary MPGN.