week 10 - immunocompromised host

Question 1

What does SPUR stand for? (Infections that’s suggest underlying immune deficiency)

Answer 1

S - severe
p- persistent
u- unusual - site of infection
R- recurrent

Question 2

What is primary I’D

Answer 2

Intrinsic defect - single gene disorder, polygenic, HLA polymorphism

Question 3

What is secondary I’D

Answer 3

Underlying disease or condition affecting immune components - eg under production or increased catabolism

Question 4

Which cell type is mainly responsible for primary I’D

Answer 4

B cell - antibody deficiency

Question 5

What are the common defects in B cells that results in I’D

Answer 5

Inability of B cell to mature in to plasma
B cell unable to switch to IgA
Impaired B cell development - Brutons disease - X linked
Unknown
Cd40 ligand on activated T cells - so can’t switch from IgM to IgG

Question 6

How does a typical ID patient present?

Answer 6

Recurrent upper and lower resp bacterial infections - bronchiectasis
Gi complications - giardia
Arthropathies
Lymphoma and gastric carcinoma

Question 7

What is the typical management of ID

Answer 7

Prophylaxis - ABx
Ig replacement therapy
Manage resp function
Avoid unnecessary exposure to radiation

Question 8

What are some examples of clinically important phagocyte deficiencies causing ID

Answer 8

Cyclic neutropenia - cause is unknown
Leukocyte adhesion deficiency LAD - defect in adhesion to endothelium
chronic granulomatous disease - lack of respiratory burst
Chediak- higashi syndrome - failure of phagolysosome

Question 9

Presentation of patients with phagocyte def..

Answer 9

Prolonged and recurrent infections - skin, mucous membranes
Osteomyelitis
Inflammatory problems - granulomas

Question 10

How do you manage a patient with phagocyte deficiency

Answer 10

Prophylactic ABx 
Surgical
Interferon-g
Steroids
Stem cell transplantation

Question 11

What staphylococcal infection would you look for in CGD

Answer 11

Staph catalase positive

Question 12

What are some examples of T cell deficiencies

Answer 12

Di George syndrome - defect in thymus embryogenesis and incomplete development
Severe combined immuniodeficiency - SCID

Question 13

How does a patient with SCID present

Answer 13

Failure to thrive
Deep skin and organ abscess
High susceptibility to bacterial, viral and fungal infections - PCP, Vzv, Cmv, ebv

Question 14

How do you manage SCID

Answer 14

Short term - no live vaccines, only irradiated CMV blood products, aggressive tangents of infections and prevent new ones
Long term - bone marrow or stem cell transplant or gene therapy

Question 15

What are causes of secondary immune def?

Answer 15

Splenectomy

Decreased production of immune come entente eg malnutrition, HIV

Question 16

Why is the spleen important

Answer 16

Immune function- bloodbourne pathogens eg encapsulated bacteria
Antibody production
Splenic macrophages - removal of opsonised microbes and removal of immune complexes

Question 17

How does asplenic patient present

Answer 17

Increased susceptibility to encapsulated bacteria, sepsis

Question 18

What is the management of asplenic patient

Answer 18

Life long prophylaxis
Immunisation against encapsulated bacteria
Carry a card

Question 19

Why do patients with cancer have an increased risk of ID

Answer 19

Chemotherapy induced neutropenia
Chemotherapy induced damage to mucosal barriers (bc continually dividing)
Vascular catheters - allows gram positive bacteria to get into the blood stream

Question 20

Example of a secondary ID Due to loss of production or increased catabolism

Answer 20

Burns

Question 21

What investigation are used to diagnose ID

Answer 21

General - FBC
Humural/antibody immunity - IgG, IgA +|- IgE
IgG subclasses
IgG levels to specific previous vaccines

Question 22

What is an immuno compromised host?

Answer 22

State in which the immune system is unable to respond appropriately and effectively to infection