Infection (increased susceptibility)

Last updated: Tuesday, 14, December, 2010
OrganismsAppropriate Tests

The causative organisms most frequently associated with the predisposing conditions are listed.

See also Immunodeficiency and Alcholoism


Infections are usually bacterial or fungal.

See also Neutropenia and Febrile neutropenia.

Pseudomonas aeruginosa

Escherichia coli

Klebsiella pneumoniae

Staphylococcus aureus

Streptococcus pyogenes

Candida spp

See Candidiasis.

Aspergillus spp

See Aspergillosis.

Mucor spp

See Mucormycosis.

Cell mediated (T cell) immune dysfunction

Particularly in patients on steroid and immunosuppressive therapy (eg, fludarabine); in those with HIV infection; and following transplantation.

Infections are commonly due to intracellular organisms, immunosuppressive treatment and steroid therapy.

Herpes simplex

See Herpes simplex infection.

Herpes zoster

See Varicella zoster infection.


See Cytomegalovirus infection.

Measles virus

See Measles.

Mycobacterium  spp

See Mycobacterial infection.

Nocardia spp

See under Pneumonia - immunocompromised host.

Salmonella spp

Legionella pneumophila

See under Pneumonia - atypical. See also Legionella infection

Listeria monocytogenes

See Listeriosis.

Cryptococcus neoformans

See Cryptococcal infection.

Candida spp

See Candidiasis.

Pneumocystis jiroveci

See under Pneumonia - immunocompromised host.

Toxoplasma gondii

See Toxoplasmosis.

Cryptosporidium sp

See Cryptosporidial infection.

Strongyloides stercoralis

Humoral immune dysfunction

Deficient antibody production, particularly in patients with multiple myeloma, chronic lymphocytic leukaemia, nephrotic syndrome, and primary immunodeficiencies.

Streptococcus pneumoniae

Haemophilus influenzae

  Neisseria meningitidis

Giardia intestinalis

See Giardiasis.

Complement deficiency and/or dysfunction

See under Immunodeficiency - primary.

Streptococcus pneumoniae

See under Pneumonia.

Neisseria meningitidis

Neisseria gonorrhoeae

Neutrophil dysfunction

Infections are commonly due to organisms of low virulence.