- B-cell immunodeficiencies (pyogenic and sinopulmonary infections, especially by encapsulated bacteria. See Asplenia)
- X-linked (Bruton) agammaglobulinemia
- Selective IgA deficiency
- Common variable immunodeficiency
- T-cell immunodeficiencies (more abnormalities)
- DiGeorge syndrome
- Autosomal dominant hyper-IgE syndrome (Job syndrome)
- IL-12 receptor deficiency
- Chronic mucocutaneous candidiasis
- IPEX syndrome
- Combined immunodeficiencies
- Neutrophil and phagocyte disorders
- Chronic granulomatous disease (CGD)
- Leukocyte adhesion deficiency type 1
- Chédiak-Higashi syndrome
- Myeloperoxidase deficiency
- Complement system > Complement deficiencies
Common Pathogens and Mechanisms
| Immunodeficiency Type | Common Pathogens | Common Infection Sites | Underlying Mechanism |
|---|---|---|---|
| B-cell Deficiencies | - Encapsulated bacteria (S. pneumoniae, H. influenzae, M. catarrhalis) - Giardia lamblia - Nonenveloped viruses (enterovirus, rotavirus) | - Sinuses - Ears - Lungs - Bloodstream - GI tract | Decreased or absent antibody production impairs opsonization and neutralization of pathogens, especially encapsulated bacteria that require antibody-mediated clearance |
| T-cell Deficiencies | - Viruses (CMV, EBV, VZV, HSV) - Fungi (Candida, P. jirovecii) - Mycobacteria - Intracellular parasites | - Skin/mucous membranes - Lungs - CNS - Systemic dissemination | Impaired cell-mediated immunity against intracellular pathogens, defective cytokine production, and decreased killing of infected cells |
| Combined Immunodeficiencies | - Broad spectrum of pathogens - Bacteria, viruses, fungi, protozoa - Opportunistic infections - Live vaccine strains | - Multiple organ systems - Lungs - GI tract - Skin - Systemic infections | Profound defects in both cellular and humoral immunity, affecting both adaptive and innate immune functions |
| Neutrophil/Phagocyte Disorders | - Catalase-positive bacteria (S. aureus, Burkholderia, Serratia, Nocardia) - Fungi (Aspergillus, Candida) - Gram-negative bacteria | - Skin/soft tissue abscesses - Lungs - Liver abscesses - Lymph nodes - GI tract | Defective phagocyte recruitment, ingestion, or killing of pathogens; impaired respiratory burst (in CGD); defective chemotaxis |
| Complement Deficiencies | - Encapsulated bacteria - Neisseria species (meningitidis, gonorrhoeae) - S. pneumoniae - H. influenzae | - Meninges - Bloodstream - Respiratory tract - Urogenital tract | Impaired opsonization and bacterial killing (like B cell deficiency) |
Clinical Pearls:
- Recurrent sinopulmonary infections with encapsulated bacteria suggest antibody deficiency
- Mucocutaneous candidiasis points toward T-cell dysfunction
- Severe, life-threatening infections beginning in early infancy suggest SCID
- Deep-seated abscesses with catalase-positive organisms suggest chronic granulomatous disease
- Recurrent Neisserial infections are hallmarks of terminal complement deficiencies