10. Immunocompromised host Flashcards

1
Q

“immunocompromise” is?

A

state in which the immune system is unable to respond appropriately and effectively to infections microorganisms

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2
Q

“immunodeficiency” is?

A

immunocompromise caused by defect in 1 or more components of immune system

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3
Q

describe the 2 types of immunodeficiency

A
1. primary - congenital
due to intrinsic gene defect (275 genes)
- missing protein 
- missing cell
- non-functional components
  1. secondary - acquired
    due to underlying disease/treatment
    - decreased production/function of immune components
    - increased loss or catabolism of immune components
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4
Q

Which 4 characteristics of infections suggest underlying immune deficiency?

A

SPUR:

Severe
Persistent (despite treatment)
Unusual (site or microogranism)
Recurrent

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5
Q

10 warning signs of PIDs in children?

A
  1. 4+ new ear infection <1yr
  2. 2+ serious sinus infections <1yr
  3. 2+ pneumonias <1yr
  4. recurrent, deep skin or organ abscesses
  5. persistent thrush in mouth or fungal infection on skin
  6. 2+ deep-seated infections inc. septicaemia
  7. 2+ months on antibiotics with little effect
  8. need for IV antibiotics to clear infections
  9. failure of infant to gain weight/grow normally
  10. family history of PID
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6
Q

10 warning signs of PID in adults?

A
  1. 2+ new ear infections <1yr
  2. 2+ new sinus infections <1yr
  3. 1 pneumoniae/yr for >1yr
  4. recurrent viral infections
  5. recurrent deep abscesses of skin or internal organs
  6. persistent thrush or fungal infection on skin or elsewhere
  7. infection with normally harmless tuberculosis-like bacteria
  8. recurrent need for IV antibiotics to clear infections
  9. chronic diarrhoea with weight loss
  10. family history of PID
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7
Q

what are the limitations of the 10 warning signs

A
  1. lack of pop-based evidence (e.g. family history, failure to thrive)
  2. PID patients with diff. defects/presentations (infections with subtle presentation, T cells/ B cells/ phagocytes/ complement)
  3. PID patients with non-infectious manifestations (autoimmunity, malignancy, inflammatory responses)
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8
Q

which malignancy is common in PIDs

A

lymphoma

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9
Q

name the 4 main types of PID in commoness order, and give an example of each

A
  1. predominantly antibody deficiencies (65%)
    - COMMON VARIABLE IMMUNODEFICIENCY (CVID)
    - X-LINKED AGAMMAGLOBULINAEMIA (BRUTON’S DISEASE)
    - SELECTIVE IgA DEFICIENCY (usually asymptomatic)
  2. combined B and T cell
    - SEVERE COMBINED IMMUNODEFICIENCY (SCID)
  3. phagocytic defects
    - CHRONIC GRANULOMATOUS DISEASE
  4. other cellular immunodeficiencies
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10
Q

what PIDs do different ages of symptom onset suggest

A
  • <6 mths = T cell or phagocyte defect
  • > 6 mths - <5 yrs = B cell/antibody or phagocyte defect
  • > 5 yrs = B cell/antibody defect, complement defect or secondary immunodeficiency
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11
Q

which microbes are commonly associated with complement deficiency

A

encapsulated bacteria, e.g. Neisseria spp, streptococci, H. influenzae

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12
Q

which infections are associated with C3 or C5-C9 deficiency?

A

C3 = pyogenic infections

C5-C9 = meningitis, sepsis and arthritis

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13
Q

which condition results from C1 inhibitor deficiency?

A

angioedema

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14
Q

which microbes are associated with phagocytic defects?

A

Bacteria: S. aureus, P. aeruginosa, non-tuberculous mycobacteria

Fungi: Candida spp., Aspergillus spp.

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15
Q

which infections are associated with phagocytic defects?

A
  • skin/mucous infections
  • deep seated infections
  • invasive fungal infections (ASPERGILLOSIS)
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16
Q

which specific infection is indicative of antibody deficiencies

A

giardia lamblia (protozoa) GI infection

17
Q

which microbes are associated with antibody deficiencies?

A

Bacteria: streptococci, staphylococci, H. influenzae, P. aeruginosa, Mycoplasma pneumoniae (upper resp. infections)

Protozoa: Giardia lamblia

18
Q

which infections are associated with antibody deficiencies

A
  • sinorespiratory infections

- GI infections

19
Q

which conditions are associated with antibody deficiencies

A
  • arthropathies
  • malignancies
  • autoimmunity
20
Q

which microbes are associated with T cell deficiencies

A

Bacteria: same as antibody deficiency + intracellular bacteria like S. typhi, L. monocytogenes, and non-tuberculous mycobacteria

All viruses

Fungi: Candida spp, Aspergillus spp, Cryptococcus neoformans, Histoplasma capsulatum

Protozoa: Pneumocystis jirovecii, Toxoplasma gondii, Cryptosporidium parvum

21
Q

which conditions are associated with T cell defects?

A
  • opportunistic infections
  • deep skin and tissue abscesses
  • failure to thrive
  • death if not treated
22
Q

what is supportive treatment for PID?

A
  1. infection prevention (prophylactic antimicrobials)
  2. treat infections promptly and aggressively (passive immunisation)
  3. nutritional support (vitamins A/D)
  4. use UV-irradiated CMVned blood products only
  5. avoid live attenuated vaccines in Ps with severe PIDs (SCID)
  6. avoid non-essential exposure to radiation
23
Q

what is the specific treatment for antibody deficiencies?

A

regular immunoglobulin replacement therapy (IVIG or SCIG)

24
Q

what is the specific treatment for SCID

A

Haematopoietic Stem Cell Therapy (90% success), but:

  • need donor match
  • must be performed within 3 1/2 mths
25
Q

name commorbidities of PID

A
  1. autoimmunity
  2. malignancies (esp. lymphoma and leukaemia)
  3. organ damage (e.g. lungs) if untreated
26
Q

what is immunoglobulin replacement therapy and when is it used

A

concentrated form of Igs given either IV every 3 wks or Sc (subcutaneous) in young patients

used to treat CVID, XLA and hyper-IgM syndrome

27
Q

what are the main causes of secondary immune deficiencies?

A

decreased production of immune components

  1. malnutrition - main cause
  2. infection (HIV)
  3. liver diseases (as liver products acute phase proteins, etc.)
  4. lymphoproliferative diseases - i.e. cancer and chemotherapy (causes neutropenia)
  5. splenectomy
28
Q

name possible causes for splenectomy/hyposplenism

A
  • infarction (eg sickle cell anaemia)
  • trauma
  • autoimmune haemolytic disease
  • infiltration (tumour)
  • coeliac disease
  • congenital
29
Q

why is the spleen so important

A

largest lymphoid organ

  1. only organ to fight blood-borne pathogens, inc. encapsulated bacteria
  2. antibody production:
    • acute response: IgM production (pentameric - 5 fold activation of complement)
    • long term protection: IgG production (best opsonin)
  3. splenic macrophages:
    • removal of opsonised microbes
    • removal of immune complexes
30
Q

what are the complications of splenectomy

A
  1. increased susceptibility to encapsulated bacteria: H. influenzae, Strep. pneumoniae, N. meningitidis
  2. OPSI (overwhelming post-splenectomy infection): sepsis and meningitis
31
Q

describe the management of asplenic patients

A
  1. penicillin prophylaxis (life-long)
  2. immunisation against encapsulated bacteria
  3. medic alert bracelet
32
Q

why does haematological malignancy increase infection susceptibility?

A
  1. chemotherapy-induced neutropenia
  2. chemotherapy-induced damage to mucosal barriers
  3. vascular catheters (e.g. Hickman line)