Microscopic polyangiitis following recurrent Staphylococcus aureus bacteremia and infectious endocarditis.

Secondary vasculitis resulting from unusual pathologic expressions of infections has been described and has important clinical significance. Infectious agents have also been implicated in the pathogenesis of different primary systemic necrotizing vasculitides. Infectious endocarditis is of particular importance in the differential diagnosis of a patient presenting with ANCA associated vasculitis. We report a well-documented case of a patient with recurrent Staphylococcus aureus bacteremia who developed bacterial endocarditis and also fulfilled the Chapel Hill Conference definitions for microscopic polyangiitis. To the best of our knowledge, it is the second case of bacterial endocarditis associated with both pANCA and anti-MPO specificity that fulfilled definitions for systemic necrotizing vasculitis. We emphasize the potential pathogenic role of infection as the trigger factor for the development of systemic vasculitis.