Antibody deficiencies and complement deficiencies are the most frequent Primary immunodeficiencies (PIDs) in adults, and are associated with greatly increased susceptibility to recurrent and/or severe bacterial infections - especially upper and lower respiratory tract infections and meningitis. The literature data suggest that PIDs are under-diagnosed in adults. The current European and US guidelines advocate screening adults for PIDs if they present recurrent benign especially upper and lower respiratory tract infections, or if they have experienced at least two severe bacterial infections and/or have a recurrent need for intravenous antibiotics. The objective of the demonstrate the interest of PIDs screening in adult patients who present such recurrent infections and/or after the first severe bacterial infection, especially when the patients do not present with known, etiologically relevant comorbidities.

Inclusion Criteria:

• 18-65 yrs old patients
• ≥ 2 bacterial upper or lower respiratory tract infections/years, for at least 2 years, or
• ≥ 1 severe bacterial upper or lower respiratory tract infection requiring hospitalization and IV antibiotics, or
• ≥ 1 invasive infection (meningitis, bacteriemia, arthritis) due to Streptococcus pneumoniae, group A Streptococcus, Haemophilus influenzae, Neisseria meningitidis or Neisseria gonorrhoeae

Exclusion Criteria:

• concomitant, systemic comorbidity that predisposes to infection (solid or hematological cancer, diabetes mellitus, severe alcohol or intravenous drug abuse, chronic liver or kidney failure, human immunodeficiency virus infection, anatomic or functional asplenia, drug-induced 1 neutropenia, or solid organ or hematopoietic stem cell transplantation).
• the presence of a local predisposing factor: cigarette smoking (> 5 pack-year and/or 5 cigarettes/day), underlying infection (tuberculosis, influenza…), chronic obstructive pulmonary disease, cystic fibrosis or bronchiectasis for pulmonary infections; cerebrospinal leak or preceding upper respiratory tract (URT) infections for non-meningococcal meningitis; oral, dental or skin condition for GAS infections
• use of corticosteroids, non-steroidal anti-inflammatory drugs, immunosuppressants or cytotoxic chemotherapeutics
• PID diagnosed before the infectious episode in question.
• current or recent pregnancy
• hospital-acquired infection (including infections of prostheses).