Abstract
Eculizumab, a humanized monoclonal antibody to complement C5, is a therapeutic drug for atypical hemolytic-uremic syndrome (aHUS) that inhibits the terminal pathway of complement. Patients on eculizumab therapy may become more susceptible to infection with capsule-forming bacteria, including meningococci. Therefore, meningococcal vaccination is required for patients who are on eculizumab therapy. However, the means to prevent meningococcal infection in infants who cannot be vaccinated with the available meningococcal vaccine have not yet been established internationally. In two infants with aHUS at 4-5 months after birth, prophylactic oral amoxicillin was administered, and meningococcal infection was not detected during the period between the initiation of eculizumab therapy and the administration of meningococcal vaccine. Neither adverse events related to amoxicillin nor thrombotic microangiopathy occurred during the treatment. Thus, oral administration of amoxicillin may be effective for preventing meningococcal infection under treatment with eculizumab in infants who have not received meningococcal vaccination.