L16 - The Immunocompromised Host

Question 1

What are the most common reasons (risk factors) for why someone would be immunocompromised?

Answer 1

Malnutrition
Infection
Primary immunodeficiency 
Chemotherapy 
Malignancies

Question 2

An immunocompromised host is one in which the immune system is unable to respond appropriately and effectively to infectious microorganisms
T/F?

Answer 2

T

Question 3

What are some warning signs for an immunodeficiency?

Answer 3

SPUR
Severe - life threatening illnesses
Persistent - diseases persists even after microbial treatment
Unusual - Unusual pathogens and/or sites of infection
Recurrent - infections keep coming back

Also

• family history
• autoimmunity
• sepsis
• failure to thrive (ability to gain weight/live normally)

Question 4

Primary immunodeficiencies can be split into those caused by antibody (/B cell) defects (65%), those caused by T cell defects (15%) and those caused by phagocytosis defects. Give an example of each

Answer 4

antibody defects -IgA deficiency
T cells - Di George syndrome (thymus defect)
Phagocytic defects - Chronic granulomatous disease (note patients have areas on inflammation called granulomas in various tissues which can result in damage) - defect in respiratory burst

Question 5

When diagnosing primary immunodeficiency it is important to ask about age of onset. If the patients onset is of the following ages what does it suggest a defect in?:
A) < 6 months
B) 6 months - 5 years old
C) after 5 years old

Answer 5

A) T cell/phagocyte defect
B) antibody/phagocyte defect
C) B cell/antibody/complement or a secondary immunodeficiency resultant from chemo etc

Note T cell under 6 months because the baby has B cell antibody protection given by mother

Question 6

Describe a classical presentation of a patient with chronic granulomatous disease

Answer 6

Patient has had multiple staphylococcal abscesses over the body since the age of four weeks. Admitted regularly for staphylococcal infections. Height and weight well below average. Brothers similarly affected/frequent fungal infections (e.g. pulmonary aspergillus infections)

Note - CGD is X linked. It is a phagocyte deficiency. Phagocyte deficiencies are particularly susceptible to staphylococcal infections. He is showing failure to thrive. Regular skin abscesses. Note that also phagocytic defects are commonly associated with deep seated organ infections too

Question 7

Suggest what element of the immune system there is a deficiency in the following cases

1) meningitis infection recurrent, sepsis too. Adult on set
2) regular skin infections. Presence of deep seated organ infections caused by staphylococci
3) Regular protozoan infections (commonly guardians lambkins) GI infections, associated malignancy/autoimmunity
4) Opportunistic infections, failure to thrive, deadly diseases

Answer 7

1) complement
2) phagocytes e.g. CGD
3) antibody deficiency e.g. IgA deficiency/Britons disease
4) T cell e.g. SCID/Di George syndrome

Question 8

Outline the supportive treatment for patients with primary immunodeficiencies and some specific ones

Answer 8

Antimicrobials, nutritional support, treat infections aggressively, avoid live vaccines

Specific - where possible Ig’s in those deficiencies. Haemopoietic stem cell transplant in SCID patients

Question 9

What are potential complications of primary infection with chicken pox as an adult?

Answer 9

Reye syndrome - acute encephalopathy with a fatty liver

Question 10

What is the specific treatment in severe cases of shingles and chicken pox?

Answer 10

Acyclovir

Question 11

What drug do we give patients who are immunocompromised and in neutropenic sepsis?

Answer 11

Tazocin (broad spec antibiotic) otherwise we’d give co-amoxiclav (normal broad sepc antibiotic) AND we’d give recombinant G-CSF to boost levels!

Question 12

What organisms are we targetting if we suspect sepsis has arrived from a central line?

Answer 12

gram positive organisms such as s aureus coagulase negative staph and enterococci - good drug for this is vancomycin

Question 13

What is the viridans strep that commonly causes native endocarditis when it travels via the blood due to bleeding gums?

Answer 13

s. mutans

Question 14

How can you test if someone has had an infection before?

Answer 14

Test for IgG antibodies to the disease

Question 15

What virus causes both chicken pox and shingles?

Answer 15

Varicellar-zoster virus (belongs to herpes simplex family)