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host microbe interactions Flashcards

(47 cards)

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1
Q

wha tis the initial protection provided by the immune system

A

physical barriers

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2
Q

what are the two components of the immune system?

A

innate (phagocytes/ NK cells)

acquired/adaptive (B cells/ T cells)

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3
Q

different parts of the immune system control

A

different types of organisms

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4
Q

what is the role of physical barriers?

A

protection from infection

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5
Q

what increases the risk of infection?

A

damage/ inflammation to these barriers

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6
Q

skin

A

Keratinocytes secrete antimicrobial peptides (defensins)
Sebaceous/sweat glands secrete microbe-inhibiting substances (e.g. fatty acids)
Antigen-presenting cells in skin

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7
Q

mucosa of respiratory?GI/GU tract

A

Antimicrobial substances e.g. lysozyme
Secretory immunoglobulin A (IgA)
Gastric acid

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8
Q

susceptibility due to impaired barrier - skin

A

Eczema, psoriasis, erythroderma
Tinea pedis / cracking of skin
Ulcers / pressure sores

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9
Q

susceptibility due to impaired barrier - lungs

A

Cystic fibrosis / Bronchiectasis
COPD
Poor swallow (often due to neurological illness, e.g. previous stroke)

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10
Q

susceptibility due to impaired barrier - GI

A

Mucositis secondary to chemotherapy
Inflammatory bowel disease
Bowel cancer

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11
Q

susceptibility due to impaired barrier - GU

A

Impaired bladder emptying / catheterisation

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12
Q

what parts of the immune system fight against infection?

A

phagocytes
T-lymphocytes
B-cells

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13
Q

what are phagocytes?

A

neutrophils and macrophages

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14
Q

what is the role of phagocytes?

A

ingest organisms following opsonisation, killing via oxygen dependent or independent mechanisms

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15
Q

phagocytes are responsible for controlling infection from?

A

bacteria and fungi
Strep, Staph, coliforms etc.
Aspergillus, Candida

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16
Q

deficiencies or impaired function of phagocytes tend to be seen in?

A 
Haematological malignancy (esp acute leukaemia, myelodysplasia)
Cytotoxic chemotherapy
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17
Q

role of helper T-lymphocytes (CD4+)

A

CD4+ T cells activate phagocytes to kill microbes

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18
Q

role of cytolytic T-lymphocyte (CD8+)

A

CD8+ T cells destroy infected cells containing microbes or microbial proteins

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19
Q

T lymphocytes control?

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A

large number of infections, co-ordinate responses

20
Q

deficiency of T-lymphocytes causes a range of susceptibilities in?

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A

Viruses, fungi, mycobacteria and parasites (mostly intracellular organisms)

21
Q

deficiencies of T-lymphocytes tend to be seen in?

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A 
HIV infection (acquired deficiency in CD4+ lymphocytes)
Lymphoma
Primary immunodeficiency syndromes (e.g. SCID)
22
Q

where do B lymphocytes mature?

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A

into the plasma cell and produce immunoglobulins

23
Q

immunoglobulins protect against?

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A

recognised antigens
IgM produced first – weak affinity
IgG produced subsequently – strong affinity

24
Q

Antibodies also help?

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A

opsonize microbes for ingestion by phagocytes:

bacteria and virus

25
deficiencies/imapired function of antibodies tend to be seen in
Myeloma (paraproteinaema with immune paresis) Primary immunodeficiency syndromes Certain immune suppressants (e.g. rituximab)
26
HIV infects?
CD4+ T lymphocytes
27
how does HIV cause a reduction of CD4+ lymphocytes?
progressive decline, resulting in cell mediated immunity
28
those with HIV have a high risk of?
invasive pneumococcal (S. pneumonia) disease (bacteraemia/meningitis/empyema etc.) irrespective of CD4 count
29
CD4 <350
Mycobacterium tuberculosis, candidiasis
30
CD4<200
Pneumocystis jirovecii, Toxoplasma gondii
31
CD4<100
Cryptococcus neoformans, Cytomegalovirus (CMV)
32
hyposplenism
decreased spleen function
33
splenectomy
trauma ITP lymphoma etc
34
"functional: hyposplenism
sickle cell, cirrhosis, coeliac disease
35
hyposplenism: host susceptibility to invasive infection from
``` encapsulated organisms Streptococcus pneumoniae (pneumococcus) Haemophilus influenzae type B (HiB) Neisseria meningitidis (meningococcus) ```
36
how to reduce risk of hyposplenism?
Risk can be reduced by vaccination (preferably before splenectomy) along with amoxicillin to prevent infection from pneumococci
37
elderly patients are:
Elderly patients more prone to infections | Less able to distinguish self from non-self – autoimmune disorders more common
38
immune system of the elderly?
Phagocytes destroy bacteria /antigen more slowly T cells respond more slowly Less antibody is produced and it binds to antigen less well Less complement is produced
39
immune suppression is caused by?
Variety of drugs used for range of conditions Aim is to reduce damage due immune response Autoimmune conditions Transplants Cancers
40
autoimmune conditions that cause immune suppression?
``` Inflammatory arthritis Vasculitis / connective tissue diseases Glomerulonephritis Inflammatory bowel disease Interstitial lung disease ITP / autoimmune haemolytic anaemia ```
41
transplants and immune suppression
``` Solid organ (kidney/heart/lung/liver/pancreas/small bowel) Bone marrow (particularly with graft vs host disease) ```
42
cancer and immune suppression
“Biologics” used especially in breast/lung/liver cancer and melanoma
43
effects of immunocompromised?
blunted response to stimuli Often do not exhibit same symptoms and signs as “normal people” Fever may be absent Lack of inflammatory response (CRP / neutrophilia) Non-specifically unwell, no localising features Often lower threshold for treatment Need to consider wider range or possible organisms
44
spectrum of immunocompromised?
Wide range of drugs used Often combinations of drugs “Level” of immunosuppression varies widely with condition treated, e.g. Acute leukaemia treated with bone marrow transplant Severe (life threatening) vasculitis / connective tissue diseases ITP / AIHA ”Mild” inflammatory bowel disease
45
steroid associations
wide range of infection | particularly strong association with fungal infections (Candida, aspergillum)
46
anti-TNFa therapy associations?
Anti-TNFa therapies (e.g. Infliximab/Etanercept) Strong association with Mycobacterium tuberculosis Fungal infections (Aspergillus in particular)
47
purine analogue associations?
(e.g. fludarabine/cytarabine) Viral infections (especially Herpes Simplex Virus and Varicella Zoster Virus) Pneumocystis jirovecii

Sepsis (8 decks)

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