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Infection * > S9 Immunocompromised Host > Flashcards

S9 Immunocompromised Host Flashcards

1
Q

What is an immunocompromised host?

A

A 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

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2
Q

What are the two main types of immunodeficiency?

A

Primary - congenital - due to a gene defect

Secondary - acquired - due to an underlying disease/treatment

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3
Q

What 3 questions need to be considered about components of the immune system that lead to an immunocompromised host? (To specify what type of deficiency it is)

A

Is the component present?

Is it in the correct number?

Is it functional?

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4
Q

When do you suspect immunodeficiency?

A

If the infection is… SPUR

Severe
Persistent
Unusual
Recurrent

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5
Q

What are the 10 warning signs of primary immunodeficiency in children?

A
  1. 4+ new ear infections within a year
  2. 2+ serious sinus infections within a year
  3. 2+ months on antibiotics with little effect
  4. 2+ pneumonia’s within a year
  5. Failure to gain weight/grow normally
  6. Recurrent, deep skin or organ abscesses
  7. Persistent thrush in the mouth/fungal infection on the skin
  8. Need IV antibiotics to clear infections
  9. 2+ deep-seated infections inc. septicaemia
  10. Family history of PID
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6
Q

How do the warning signs of primary immunodeficiency vary in adults compared to children?

A
  • 2+ new sinus infections within a year without allergy
  • chronic diarrhoea with weight loss rather than growing normally
  • recurrent viral infections
  • persistent thrush/fungal infection elsewhere as well as skin
  • infection with harmless TB like bacteria
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7
Q

What are the limitations of the 10 warning signs?

A
  • lack of population based evidence
  • everyone is different with different defects and presentations
  • some primary immunodeficiency patients have had non-infectious manifestations like malignancy
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8
Q

What are most immunodeficiencies caused by?

A

Antibody defects (about 65%)

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9
Q

What are the common types of immunodeficiency antibody defects?

A

Defects in B cell development
* x-linked agammaglobulinaemia - Bruton’s disease

Defects in antibody production

  • common variable immunodeficiency (CVID)
  • selective IgA deficiency
  • hyper-IgM syndrome
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10
Q

What is the significance of selective IgA deficiency?

A

Those with this deficiency can develop anti-IgA antibodies that means any treatment with IgA results in destruction of the IgA

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11
Q

What are the common types of immunodeficiency T cell defects?

A

Combined B and T cell defects
* severe combined immunodeficiency (SCID)

T cell defects
* Di George syndrome (thymus)

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12
Q

Why do you get combined B and T cell defects?

A

Need T helper cells for B cells to produce antibodies e.g. IgM

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13
Q

What are the common types of immunodeficiency phagocytic defects?

A

Defects in respiratory burst

* chronic granulomatous disease (CGD)

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14
Q

Based on age, when do each type of primary immunodeficiency present with symptoms?

A

If onset is younger than 6 months it is highly suggestive of T-cell or phagocyte defects

If onset is over 6 months but under 5 years this is suggestive of B-cell, antibody or phagocyte defect

If onset is over 5 years this is suggestive of B-cell/antibody/complement or secondary immunodeficiency

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15
Q

Why don’t children under 6 months present with symptoms when they have B-cell or antibody defects?

A

Because up to 6 months, they have maternal IgG antibodies

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16
Q

What is the main cause of secondary immunodeficiency?

A

Malnutrition

17
Q

What types of microbes are people more susceptible to with complement defects? What infections do they cause?

A

Neisseria species e.g. meningitis/STDs, H. influenzae, Streptococci - encapsulated bacteria

Cause pyogenic infections, meningitis, sepsis, arthritis, angioedema

18
Q

What types of microbes are people more susceptible to with phagocytic defects? What infections do they cause?

A
  • Staphylococcus aureus (cellulitis), Pseudomonas aeruginosa (cystic fibrosis)
  • Candida species, Aspergillus species

Skin/mucous infections, deep seated infections, invasive fungal infection (aspergillosis)

19
Q

What types of microbes are people more susceptible to with antibody defects? What infections do they cause?

A
  • Streptococci, Staphylococci
  • enteroviruses
  • Giardia lamblia

Infections at mucosal sites - sino-respiratory infections, GI infections, malignancies

20
Q

What types of microbes are people more susceptible to with T-cell defects? What infections do they cause?

A
  • encapsulated and intracellular bacteria e.g. Salmonella typhi
  • all viruses
  • Candida species, Aspergillus species
  • Toxoplasma gondii, Cryptosporidium parvum

Death if not treated, deep skin and tissue abscesses, opportunistic infections

ALL TYPES OF MICROBES

21
Q

What do people with chronic granulomatous disease (CGD) present with?

A
  • pulmonary aspergillosis

* skin infections

22
Q

If the condition effects women more then men in the family, which immunodeficiency is it likely to be?

A

Bruton’s disease (B cell deficiency)

23
Q

What supportive treatments are suggested for PIDs?

A
  • infection prevention - prophylactic antimicrobials
  • treat infections quickly and aggressively
  • nutritional support e.g. Vits A and D
  • avoid live vaccines in patients with severe PIDs like SCID
  • use specific safe blood products only
24
Q

What specific treatments are suggested for PIDs?

A
  • regular immunoglobulin therapy

* haematopoietic stem cell therapy (for SCID)

25
Q

What do you need to consider in the management of PIDs?

A

Any comorbidities e.g. autoimmunity and malignancies, organ damages

26
Q

What conditions is immunoglobulin replacement therapy (IRT) used to treat?

A
  • CVID
  • Bruton’s disease
  • Hyper-IgM syndrome
27
Q

How can immunoglobulin replacement therapy be given?

A

By IV

By subcutaneous injections in young patients

28
Q

What can cause secondary immune deficiencies?

A

Decreased production of immune components

  • malnutrition
  • infection e.g. HIV
  • liver diseases
  • haematological malignancies
  • therapeutic treatment e.g. corticosteroids
  • SPLENECTOMY

Increases loss of immune components

  • burns
  • protein losing conditions e.g. nephropathy and enteropathy
29
Q

How can having a heamatological malignancy cause immunodeficiency?

A
  • chemotherapy can cause neutropenia
  • chemotherapy can cause damage to mucosal barriers
  • use of vascular catheters (breach barriers)
30
Q

How do you treat suspected febrile neutropenia?

A

Treat as an acute medical emergency and offer empiric antibiotic therapy immediately and asses their risk of sepsis

31
Q

What lab investigations indicate antibody/B-cell deficiencies?

A

Antibody tests

32
Q

What lab investigations indicate T-cell deficiencies?

A

Lymphocyte numbers (FBC), test T cell function

33
Q

What lab investigations indicate phagocyte deficiencies?

A

Neutrophil count (FBC), neutrophil function tests, adhesion molecule (LAD) expression

34
Q

What lab investigations indicate, complement deficiencies?

A

Test for individual complements are complement function

Infection * (18 decks)

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