Core Immunology - Infections and Immunocompromised (15) Flashcards Preview

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Flashcards in Core Immunology - Infections and Immunocompromised (15) Deck (39):
1

Immunocompromised

Disruption of specific defence of an organ/system (humoral/cellular)

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Humoral immunity

Antibody led

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Cellular immunity

T/B cells

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Innate defences

- Skin
- Interferons, complement, lysozyme, acute phase proteins
- Mucous membranes
- Normal commensal flora in gut

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How are mucous membranes an innate defence?

Tears, urine flow, phagocytes

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Example in the lungs

Cystic fibrosis - goblet cells, much-ciliary escalator

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Classification of immunodeficiencies

- Congenital/Primary
- Acquired/Secondary

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What is 2nd line of defence?

Neutrophil

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What is a qualitative defect of neutrophils?

Lose ability to kill/chemotaxis

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What is a quantitative defect of neutrophils?

Less present

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Qualitative chemotaxis neutrophil defect

Rare, congenital, inadequate signalling/abnormality in receptors/NE movement

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Qualitative killing power neutrophil defect

Inherited, NE fail to mount respiratory burst in phagocytosis, deficient in NADPH oxidase - H2O2 not formed, at risk of staph aureus (Chronic Granulomatous Disease)

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Cause of quantitative defects (Neutropenic)

Cancer treatment, bone marrow malignancy, aplastic anaemia caused by drugs

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Quantitative defect complications

Over half develop infection - highly lethal (50% pseudomonal infections will die in 24hrs if not treated)

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Neutropenic bacterial infections

Gram neg bacilli (E.coli), Gram positive cocci (S.aureus), normal flora (coagulase neg staph)

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Neutropenic fungal infections

Candida, Aspergillus

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Treatment of neutropenic infections

Gentamicin and antipseudomonal penicllin (cabanpenem then antifungals)

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GCSF

Granulocyte stimulating factors - gets immune system working again

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Congenital T cell deficiencies

Rare

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Acquired T cell deficiencies

- Drugs (ciclosporin after transplantation/steroids)
- Viruses (HIV)

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T cell deficiency opportunistic pathogens - bacterial

Listeria monocytogenes (food),

Mycobacteria – MTB, MAI

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T cell deficiency opportunistic pathogens - viral

Leukaemia and transplant - HSV, CMV, VZV

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T cell deficiency opportunistic pathogens - fungal

Candida, cryptococcus

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T cell deficiency protozoan - Cryptosporidium parvum (sporozoa)

Occysts spread by cattle/humans, faecal-oral, recover after 3 weeks (T deficient longer)

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T cell deficiency protozoan - Toxoplasma gondii (sporozoa)

Cats/humans infected by contact with cat faeces/transplanted heart with bradyzoites present, lesion in brain/neurological signs (immunocompetent asymptomatic)

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T cell deficiency protozoan - Strongyloides sterocoralis (Nematode)

Larvae penetrate skin and migrate, normally asymptomatic/rash, immunocompromised huge invasion of tissues/gram -ve septicaemia as larvae move, suspect in tropical countries/old, picked up on feet - dormant

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Hypogammaglobulinaemia

Antibody problems, encapsulated bacteria (S.pneumoniae in resp tract/Giardia lambila/cryptosproidium in GIT)

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Congenital Hypogammaglobulinaemia

Rare

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Acquired Hypogammaglobulinaemia from

Multiple myeloma, chronic lymphocytic leukaemia, burns

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Compliment deficiency

Hereditary and rare, encapsulated bacteria, need complement to help kill organisms, earlier defect in pathway greater number of organisms may infect

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Complement deficiency illnesses

Neisseria meningitidis and S.pneumoniae lysis not achieved by MAC/opsonisation (50-60% patient 1 epsiode of disease)

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Spleen

Source of complement and antibody producing B-cells, removes opsonised bacteria from blood

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Causes of splenectomy

Traumatic, surgical, functional (sickle cell anaemia)

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Infections in splenectomy patients

Strep penumoniae, H. influenza type B, N. meningitis, malaria (high mortality - prophylactic penicillin)

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Biologics

Antibodies/other peptides, inhibit inflammatory cytokine signals (TNF/T-cell activation/deplete B-cells)

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Biologics used for

RA

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Biologics increased risk of

TB, Herpes zoster, Legionella pneumophila, Listeria monocytogenes

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Organ transplant e.g.

Liver in HCV/paracetamol OD, stem cells in haematological malignancy

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Anti-rejection treatment

Suppresses cytoxotic and NK cells

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