Neutropenia
- Gram-negative enteric organisms
- Pseudomonas
- Gram-positive cocci, eg, S. aureus, S. epidermidis
- Candida
- Aspergillus and other fungi
Cellular immune defect
(HIV, lymphoma, immunosuppressive drugs)
- Bacteria: Listeria, Legionella, Salmonella, Mycobacterium
- Viruses: herpes simplex virus, varicella, cytomegalovirus
- Fungi: Cryptococcus, Coccidioides, Histoplasma, Pneumocystis
- Protozoa: Toxoplasma
Humoral immune defect
(congenital, multiple myeloma, chronic lymphocytic leukemia)
- Encapsulated organisms: Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis
Asplenia
(functional or anatomic)
- Encapsulated organisms: Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis
Noninfectious causes
- Transplant rejection
- Organ ischemia or necrosis
- Thrombophlebitis
- Lymphoma