Immunodeficiencies & infections

Question 1

Most Primary Immunodeficiencies are single gene defects, what are the 3 domains?

Answer 1

1) Ab deficiency due to defect in B cells

2) Cellular due to T cell defect

3) Innate due to PRRs, phagocytes or complement defect

Question 2

What about a child’s illness would make you suspect an immunodeficiency?

Answer 2

SPURR:
- Severe
- Persistant
- Unusual
- Recurrent
- Runs in family

Question 3

What infections arise from Ab deficiencies?

Answer 3

Recurrent resp bacterial infections incl Pneumococcus & H influenzae

Question 4

What type of infections arise from T cell deficiencies?

Answer 4

Opportunistic infections incl Pneumocytic Jiroveccii pneumonia (PCP) & CMV pneumonia

Question 5

What type of infections would you expect to see in a phagocyte defect?

Answer 5

Staph aureus –> Sepsis, skin inf & deep organ abscesses

Aspergillus –> Lung, bones & brain inf

Question 6

What infections do you see in complement deficiency?

Answer 6

N. Meningitidis (So meningitis)

Question 7

What could you do if you suspect Primary Immunodeficiencies?

Answer 7

Ab? –> Ab tests & measuring immune response to vaccination with common pathogens

T cell? –> Diff WCC & immunophenotyping

Complement? –> Measure complement activation & individual factors

Question 8

What’s the main secondary immunodeficiency?

Answer 8

HIV/AIDS

Question 9

How would you spot HIV/aIDS?

Answer 9

Recurrent/disseminated VZV/HSV
Opportunistic Inf e.g. CMV pneumonia or PCP
Recurrent RTIs & Persistant oral thrush
Erythematous popular rash, generalized lymphadenopathy & FTT/developmental delay

Question 10

Invasive fungal infections e.g. Candida Albicans or Aspergillus Fumigatus are often a presenting symptoms of Primary immunodeficiency. What else would cause one?

Answer 10

• Neutropenia e.g. leukaemia/chemo
• Neonates (immature immunity)
• Broadspec Abx and/or abdo surgery

And primary immunodeficiency

Question 11

What are the differences between an invasive candida vs aspergillus infection?

Answer 11

Candida:
- Endogenous
- Get from birth canal/staff’s hands
- +ve blood cultures
- Metastatic Foci

Aspergillus:
- Exogenous
- Get form air/water/environment
- -ve cultures with pulm disease
- Angio-invasive

Question 12

Who tends to get neonatal Candidaemia?

Answer 12

Low BW babies( mainly prems) in their 2nd/3rd wk

Question 13

What do you suspect in a premature neonate with sepsis syndrome, thrombocytopenia & Hyperglycaemia?

Answer 13

Neonatal Candidemia

(Clue is the hyperglycaemia, in a bacterial infection that would be low)