ENCAPSID Study : ENCApsulated Bacterial Infection and Primary, Secondary ImmunoDeficiency

Background : The occurrence of Primary immune deficiencies (PID) is rare in adults. Antibody deficiencies were the first PID to be diagnosed in adulthood and are mainly represented by common variable immune deficiency. The main manifestation of these PID are encapsulated bacterial infection which used to be recurrent and/or invasive, lead to hospitalization and have high rates of morbidity and mortality. Diagnosis of PID in adulthood may be supported by six warning signs from the European Society of Immunodeficiencies (ESID). However, their guidelines do not comprehensively describe symptoms of PID, even for patients with infections. The guidelines recommend screening adults for PID after at least two severe bacterial infections. The aim of this study is to screen for PID adult admitted to our hospital for encapsulated infection without any predisposal factor. Material and methods : * Monocentric study. Inclusion between September 218 and September 2021 * Inclusion criteria : 1. Age 18 to 65 years old 2. Invasive encapsulated infection (Streptococcus pneumoniae, Streptococcus pyogènes, Haemophilus influenzae, Neisseiria meningitidis or Neisseria gonorrhoeae ) * Exclusion criteria : 1. Medical history of PID 2. Medical history of Secondary immune deficiency (SID) 3. Local-regional factor that could predispose them to infection 4. Hospital-acquired infection * PID screening included the following: complete blood count, blood smear, immunoglobulin (Ig) isotype (IgA,M, G) and IgG subclass levels, total hemolytic complement and complement fractions (C) 3 and 4, alternative complement pathway (AP50) in case of Neisseria meningitidis (NM) infection, quantitative immunophenotyping of T, B and natural killer cells, specific antibody response to diphtheria, tetanus and pneumococcal vaccine and HIV serology. The clinical and laboratory diagnostic criteria used to identify PID were based on guidelines from the ESID and the Pan-American Group for Immunodeficiency