What is the evidence for prophylactic antibiotic treatment in patients with systemic vasculitides?

Purpose of Review: Microbial factors are supposed to play an inducing and/or reactivating role in many of the idiopathic systemic vasculitides. This review evaluates the evidence that microbes are involved in the etiopathogenesis of the disease focusing on possibilities for antimicrobial intervention.
Recent Findings: The clinical presentation of hepatitis B virus (HBV)-associated polyarteritis nodosa (PAN) is different from that of non-HBV-PAN and requires antiviral treatment. In hepatitic C virus (HCV)-associated autoimmune diseases, type 2 cryoglobulinemia is present in 52% of cases. Chronic nasal carriage of Staphylococcus aureus is related to endonasal activity of Wegener's granulomatosis and recurrent relapses, and prophylactic treatment with co-trimoxazole is effective in reducing relapse rate.
Summary: Patients with PAN should be tested for HBV, and patients with type 2 cryoglobulinemia for HCV. When tested positive, antiviral treatment should be considered. Patients with Wegener's granulomatosis should be tested for nasal carriage of S. aureus, and prophylactic treatment with co-trimoxazole should be considered in case of persistent endonasal activity of Wegener's granulomatosis together with S. aureus carriage. The efficacy of S. aureus elimination for preventing relapses of Wegener's granulomatosis should be evaluated.