We describe two young children with pneumococcal meningitis, one of them with a complement deficiency. Our aim is to illustrate the importance of testing the complement system in young patients with severe bacterial infections and to stress the importance to respect pre-analytical conditions. We found in a child of consanguineous parents a complement factor I deficiency, which is associated with severe recurrent pyogenic infections mainly caused by Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae. We conclude that complement deficiencies are rare but immunological workup should be done in case of recurrent bacterial infections. Patients need follow up, antibiotic prophylaxis and additional vaccinations.

(BELG J HEMATOL 2020;12(2):85-9)