The Immunocompromised Host

Question 0

Describe the main reasons for a patient to be immunocompromised

Answer 0

Primary - genetic (X linked), intrinsic defect, congenital
Secondary - increased catabolism/decreased production of immune components, underlying disease
E.g. HIV, malnutrition, cancer/chemotherapy, liver disease, phagocyte deficiency (neutropenia), T cell deficiency, splenectomy, complement deficiency

Question 1

Define the term ‘immunocompromised’

Answer 1

Immune system is unable to respond appropriately and effectively to infectious microorganisms

Question 2

Understand the links between the innate and adaptive immune system and situations and illnesses where a patient is immunocompromised

Answer 2

Viruses and fungi –> T cell deficiency

Bacteria and fungi –> B cell deficiency

Question 3

Describe the management of immunocompromised patients

Answer 3

Prompt/prophylactic antibiotics
Ig replacement therapy
Anti fungal agents
Stem cell transplant

Question 4

Explain the recognition and diagnosis of an immunocompromised patient

Answer 4

Recognition - SPUR:
Severe, Persistent, Unusual, Recurrent 
Diagnosis:
FBC (neutrophil and lymphocyte count)
Complement function 
Definitive tests (molecular/gene mutations)

Question 5

Consider Aspergillus as a cause of fungal infection in the immunocompromised

Answer 5

Fungi
Produces aflatoxin - toxic, carcinogen
Grow where there is a high osmotic gradient (increased salt/sugar)
Usually immunocompromised patients are susceptible

Question 6

Consider the manifestations of varicella-zoster infections in the immunocompetent and immunocompromised host

Answer 6

Herpes virus (double stranded DNA)
Causes chickenpox and shingles (viral latency)
Spread - respiratory droplets, direct contact with lesions
Incubation period - 7-21 days
Vesicular rash –> bumps/blisters –> scabs

Question 7

Describe DiGeorge Syndrome

Answer 7

CATCH-22
Cardiac abnormalities
Abnormal facies
Thymic hypoplasia
Cleft palate
Hypocalcaemia 
Chromosome 22

Question 8

Describe SCID

Answer 8

Primary (X linked) - B&T cell deficiency
Increased susceptibility to viral and fungal infections
No live vaccines
Need stem cell transplant

Question 9

Describe the effects of asplenism

Answer 9

Decreased antibody production
Decreased splenic macrophages
Need life long penicillin prophylaxis
Increased susceptibility to encapsulated bacteria (haemophilus influenzae, neisseria meningitidis, strep pneumoniae) therefore need immunisation