Table 1.

Aetiologic diagnoses and suggestive features

Aetiology		Suggestive features and comments
Streptococcus pneumoniae		Severe alcoholism, hypogammaglobulinemia, neutropenia, drepanocytic anemia, splenectomy, polynuclear function deficiency, suppressive immunological therapy, acquired duramatral breach
Neisseria meningitidis		Complement deficiency must be suspected. However, there are no real risk groups. Classically, epidemics occur in closed populations of young adults.
Listeria monocytogenes		Extremes of age, pregnancy, hepatic cirrhosis, haemochromatosis, chronic renal failure, cellular immunodeficiency (Hodgkin's and non-Hodgkin's lymphoma, chronic lymphoid leukaemia, corticotherapy, organ transplantation)