14. Immunocompromised Host Flashcards
What is an immunocompromised host?
State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms, due to a defect in one or more components of the immune system.
What is the cause of primary immunodeficiency?
Congenital - intrinsic gene defect leading to a missing protein, missing cell or non-functional components of the immune system.
What is the cause of secondary immunodeficiency disease?
Acquired - due to an underlying disease or treatment causing either decreased production or function of immune components, or increased loss or catabolism of immune components.
What is the mnemonic for infections in a patient that suggest underlying immune deficiency?
S - severe life threatening infection.
P - persistent infection despite normal treatment.
U - unusual site of infection (deep seated infection) or microorganism.
R - recurrent infection.
What other than recurrent infections can suggest a primary immunodeficiency disease?
A family history of primary immunodeficiency disease
What 3 things can primary immunodeficiency disease patient prevent with as non-infectious manifestations?
Autoimmunity.
Malignancy.
Inflammatory responses.
Give 3 examples of primary immunodeficiency diseases that fit into the classification of ‘predominantly antibody deficiencies’.
Common variable immunodeficiency. Selective IgA deficiency (mostly asymptomatic unless have another condition eg IgG deficiency also). IgG subclass deficiency.
Give an example of a primary immunodeficiency disease that fits into the classification ‘combined T and B cell’.
Severe combined immunodeficiency (SCID).
Give an example of a primary immunodeficiency disease that fits into the classification ‘phagocytic defects’.
Chronic granulomatous disease (affects neutrophils and their ability to carry out respiratory burst).
If the onset of symptoms is at < 6 months old then what type of primary immunodeficiency does this suggest?
T-cell or phagocyte defect
If the onset of symptoms is at > 6 months old and <5 years old then what type of primary immunodeficiency does this suggest?
B-cell/antibody or phagocyte defect
If the onset of symptoms is at > 5 years old then what type of primary immunodeficiency does this suggest?
B-cell/antibody/complement or secondary immunodeficiency
What type of infections is a patient likely to get with complement deficiency causing primary immunodeficiency disease? How does this manifest in the body?
Neisseria and Strep bacteria.
Pyogenic infections, meningitis/sepsis/arthritis, angioedema.
What type of infections is a patient likely to get with phagocytic defects causing primary immunodeficiency disease? How does this manifest in the body?
Staphylococcus aureus bacteria, Candida and aspergillus fungi.
Skin/infections, deep seated infections, invasive fungal infection.
What type of infections is a patient likely to get with antibody deficiency causing primary immunodeficiency disease? How does this manifest in the body?
Strep and staph bacteria, enteroviruses.
Sinorespiratory infections, arthropathies, GI infections, malignancies, autoimmunity (eg allergies).
What type of infections is a patient likely to get with T cell defects (links to B cell defects) causing primary immunodeficiency disease? How does this manifest in the body?
Strep, staph and salmonella typhi bacteria, all viruses, candida and aspergillus fungi.
Death if not treated, failure to thrive (eg low weight), deep skin and tissue abscesses, opportunistic infections.
What do patients with chronic granulatomous disease tend to present with?
Pulmonary aspergillosis and skin infections.
Name 3 forms of supportive treatment for management of primary immunodeficiency diseases
Prophylactic antimicrobials.
Treat infections promptly and aggressively.
Nutritional support - vitamins A/D.
Use UV-irradiated CMVned blood products only.
Avoid live attenuated vaccines.
Avoid non essential exposure to radiation.
Give 2 specific treatments of primary immunodeficiency disease
Regular immunoglobulin therapy of IgG serum, which is a life long treatment eg for CVID.
SCID - hematopoietic stem cell therapy.
Give 3 comorbidities associated with primary immunodeficiency diseases
Autoimmunity.
Malignancies.
Organ damage.
Give 5 causes of secondary immunodeficiencies caused by decreased production of immune components
Malnutrition.
HIV infection.
Liver diseases.
Lymphoproliferative diseases (and chemo also).
Splenectomy (eg via autoimmune haemolytic disease).
What is the immune function of the spleen?
Immune reaction to bloodborne pathogens including encapsulated bacteria.
Antibody production (IgM and IgG).
Splenic macrophages remove opsonised microbes and immune complexes.
How do asplenic/splenectomised patients with secondary immunodeficiency disease present?
Increased susceptibility to encapsulated bacteria eg strep and neisseria. Also with overwhelming post-splenectomy infection eg sepsis and meningitis.
How would you manage an asplenic/splenectomised patient with secondary immunodeficiency disease?
Penicillin prophylaxis.
Immunisation against encapsulated bacteria.
Medic alert bracelet and card.
