Current practices in antibiotic prophylaxis for patients on complement inhibitors: a multicenter survey across ERN ERKnet centers.

BACKGROUND: Complement inhibitors such as eculizumab and ravulizumab are increasingly used to treat rare complement-mediated diseases. While effective, these therapies impair host defenses against encapsulated bacteria, leading to a heightened risk of invasive infections. Although vaccination is standard, the role and implementation of antibiotic prophylaxis remain inconsistent across clinical settings. METHODS: A survey was conducted among European Reference Network for Rare Kidney Diseases (ERN ERKNet) centers to assess current practices regarding antibiotic prophylaxis in patients receiving complement-inhibition therapy. The survey addressed four clinical scenarios-pediatric vs. adult, transplant recipient vs. non-transplant-and explored three domains: indications for prophylaxis, choice of antibiotic, and duration. RESULTS: Twenty-seven centers from 16 European countries participated. Systematic prophylaxis was widely endorsed, particularly for pediatric patients and transplant recipients. Penicillin-class antibiotics were preferred as first-line agents across all groups. In pediatric settings, phenoxymethylpenicillin and amoxicillin were most commonly used, whereas adult regimens included penicillin or fluoroquinolones for those with allergies. Most respondents recommended continuing prophylaxis throughout the duration of complement-inhibition therapy, regardless of vaccination status. The survey revealed areas of heterogeneity in practice, especially regarding allergy management and the duration of post-vaccination coverage. CONCLUSIONS: This ERKNet survey identifies prevailing practices and variation in antibiotic prophylaxis for patients receiving complement-inhibition therapy. Based on these findings, we propose consensus guidance to support harmonized, risk-adapted prophylaxis strategies across pediatric and adult populations. These guidance statements aim to address an important unmet need in infection prevention among complement-inhibited patients.