Infection 5 Flashcards

Question

With regards to brucellosis describe the: - Transmission - Symptoms - Diagnosis - Treatment

Answer 1

**Transmission:** Through skin breaks or the GI tract (Milk) **Symptoms:** Non specific, febrile (undulant fever, rising and falling) Bone/Joint involvement Epidydimitis **Diagnosis:** Generally from blood culture **Treatment:** Doxycycline and rifampicin

Answer 2

Assessment of travel guides possible diagnosis Also allows us to assess possibility of high risk infection being present

Answer 3

Requirement to consider isolation Additional protections afforded to clinicians/lab staff handling high risk specimens

Answer 4

**Influenza:** E.g. H1N1 swine flu in 2009 **Coronavirus:** E.g. SARS-CoV in 2003 (severe acute respiratory syndrome)

Answer 5

**Your examples may vary** Filoviridae - Bat - Ebola haemorrhagic fever Flaviviridae - Mosquito - Dengue and Yellow haemorrhagic fever

Answer 6

Flu-like Vomiting Diarrhoea Haedaches Confusion Rash Internal/external bleeding at 5-7 days

Answer 7

Through direct contact with infected bodily fluids

Answer 8

Bacteria Parasites Viruses Different organisms can cause differnt types of stool found in diarrhoea

Answer 9

www. cdc.gov www. who.int

Answer 10

A virus Spreads via droplets/aerosols (commonly from a cough or sneeze)

Answer 11

Fever Cough Sore throat Muscle aches Conjunctivitis In severe cases Pneumonia

Answer 12

Subtyped based on two proteins found on the surface of the viral envelope **Haemagglutinin:** Protein that causes RBCs to agglutinate (clump together) **Neuraminidase:** A protein that cleaves the glycosidic bonds of neuraminic acid monosaccharides Subtype of each (H and N) gives the overall subtype (E.g. H1N1)

Answer 13

**Antigenic drift:** Gene mutation of antigens on envelope **Antigenic shift:** The process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains. **Pandemics:** These two processes in tandem produce new subtypes of virus that are occasionally highly virulent and +/- deadly, this leading to a pandemic

Answer 14

Oseltamivir (First ever Neuraminidase inhibitor) Only in high risk patients (elderly, young, infirm) that present with onset of symptoms less than 48hrs ago Only supportive treatment for otherwise healthy adults

Answer 15

**Bacterium causes Legionnairres' disease** **A form of pneumonia** Symptoms also include: Fever Headache Chills Cough (dry or productive) Musle aches Ataxia Confusion Diarrhoea and vomiting

Answer 16

Urea and electrolytes deranged (commonly hyponatraemia) Impaired Liver function Culture would reveal gram negative bascilli of L. pneumophilius

Answer 17

Spread via aerosol Sources = Cases and soil

Answer 18

Once phagocytosed by macrophages lysosymes are unable to bind L. pneumophilia remains in the macrophage where it can replicate

Answer 19

Macrolides Fluoroquinolones

Answer 20

No response

Answer 21

**Intracellular microbes (replicate intracellularly):** Viruses Some bacteria Protozoa **Extracellular microbes (replicate extracelullarly):** Most bacteria Parasites Worms Fungi

Answer 22

Antigen presenting cells react with T lymphocytes

Answer 23

Capture of microbe Processing of microbe Presentation of antigen to T lymphocytes

Answer 24

Within lymphoid tissue: Skin - SALT (Skin associated lymphoid tissue) Mucous membranes (GastricALT, NasalALT, BronchialALT etc) Lymphoid organs (Lymph nodes, spleen) Circulation (Plasmacytoid and myeloid Dendritic cells)

Answer 25

Phagocytosis (whole microbe) Micropinocytosis (Soluble particles - random process)

Answer 26

Extracellular pattern recognition receptors (PRRs) recognise extracellular pathogens via pathogen associated molecular patterns Intracellular PRRs recognise intracellular pathogens via PAMPs

Answer 27

Dendritic cells - Lymph nodes Langehans' cells - Skin Macrophages - various tissues B cells (recognise antigen in native form) - Lymphoid tissues

Answer 28

**Extracellular:** Extracellular PAMP is recognised by extracellular PRR leading to activation of humoral immunity (Antibodies and complement) **Intracellular:** Intracellular PAMP is recognised by PRR leading to activation of cell-dependent immunity (Cytotoxic T cells, macrophages and antibodies)

Answer 29

Present Major Histocompatibility Complex (MHC) class I/II Also known as Human Leukocyte Antigens (HLA)

Answer 30

**Presenting cell:** Class I presented by all nucleated cells Class II presented by professional APCs (dendritic cells, macrophades, B cells etc) **Function:** Class I molecules presented when peptides from intracellular microbes are detected by APC Class II molecules presented when peptides from extracellular microbes are detected by APC **Responsive T cells:** Class I molecules present to CD8+ T cells (Extrcellular) Class II molceules present to CD4+ T cells (Intracellular)

Answer 31

**Co-dominant expression:** Both parental genes expressed Increases the number of MHC molecules we can express, stregthening immunity **Polymorphic genes:** Different alleles among different individuals Increases presentation of different antigens in the population

Answer 32

**Class I:** Two peptides Alpha 1, 2 and 3 regions on peptide 1 Beta 2 microglobulin subunit on peptide 2 Peptide binding site between Alpha 1 and 2 units on peptide 1 **Class 2:** Two peptides Alpha 1 and 2 units on peptide 1 Beta 1 and 2 units on peptide 2 Peptide binding site is between the two peptides

Answer 33

Broad specificity (can present a large number of peptides)

Answer 34

**Endogenous pathway:** Virus wil replicate and produce proteins These proteins are recognised as useless and directed to proteasomes where they are cleaved into small peptides These peptides are transported to the ER where MHC class I molecules can be found, if there is a match, the two form a complex This complex is exported to cell membrane to await recognition by CD8+ T cell

Answer 35

Self proteins are recognised by MHC Class I molecules but the complex is not recognised by CD8+ T cells and do not lead to activation

Answer 36

**Exogenous pathway:** Exogenous antigen from extracellular microbe is endocytosed Lysosome fuses with endosome and antigen is digested into small peptides MHC class II bearing vesicle exported from ER fuses with endosome If MHC II recognises a peptide the complex is exported to the cell membrane to be recognised by a CD4+ cell

Answer 37

**Slow progressors:** Exhibit HLA genes such as B27, B51 and B57 These are linked to the presentation of not mutating peptides that are key to virus survival This leads to a sustained and effective CD4+ response to HIV as the virus cannot mutate these key peptides without losing the ability to replicate/infect cells etc These patients are also known as Elite controllers or long term non-progressors due to this ability to effectively control viral replication **Rapid progressors:** Exhibit HLA genes such as B35 and are commonly homozygotes for HLA-I alleles Linked to the presentation of non-key peptides that the virus can readilty mutate This leads to decreased recognising of the HIV virus and hence decreased CD4+ response hence rapid progression of disease

Answer 38

**Transplant:** HLA mismatch between donor organ and recipient leads to recipient immune system attacking donor tissue (Organ rejection) **Graft versus host:** Grafted tissues such as skin begins to attack recipient cells

Answer 39

**Ankylosing spondylitis:** HLA-B27 found in 90% of patients **Insulin dependent Diabetes Mellitus:** HLA-DQ2 found in 50-75% of patients

Answer 40

Intracellular microbes can trigger a dendritic cell to present with MHC class I and II molceules hence activating CD4+ and CD8+ cells CD4+ cells activated in this way are a differnt type of CD4+ cells to that seen in humoral immunity Mechanism unknown

Answer 41

Thymus gland

Answer 42

Used to recognise MHC I and II molecules Huge genetic diversity required to recognise all MHC molecules Genetic diversity comes about via a process called gene rearrangement Creates a variable region within the TCR protein that binds to MHC

Answer 43

**CD4+:** Called T helper cells TH-1 TH-2 TH-17 **CD8+:** Cytotoxic T lymphocytes (CTL)

Answer 44

**All:** T Cell receptor - For binding to processed peptide on MHC CD3 - Co-receptor involved in signal transduction **CD4+:** CD4 protein - Recognises MHC class II molecules directly conferring specificity **CD8+:** CD8 protein - Recognises MHC class I molecules directly conferring specificity

Answer 45

**Naive TH-0 CD4+ cells bind to an APC presenting MHC class II molecules in 3 ways:** CD4 bind directly to MHC II TCR binds to the peptide presented by MHC II CD28 on the T cell binds to B7 protein on the APC **APC releases cytokines that stimulate one of two outcomes:** If the MHC II is presenting extracellular microbe fragments then the TH-0 lymphocyte becomes TH-2 or TH-17 for best humoral response If the MHC II is presenting intracellular microbe fragments (such as in the case of dendritic cells) then the TH-0 lymphocyte becomes TH-1 for best cellular immune response (TH-1 goes on to interact with CD8+ which is activated in tandem with CD4+)

Answer 46

Binding of TCR and CD4+/8+ is not enough to fully activate a T cell and therefore an extra recptor/ligand binding pair is required to bind to fully activate E.g. B7 and CD28 for CD4+ cells

Answer 47

APC (Dendritic cell) presents MHC I and II molecules and acessory activation proteins such as B7 that activate both CD4+ (into TH-1) and CD8+ cells CD8+ cells are not fully activated and require interaction with TH-1 cells to fully activate CD8+ cells are now fully activated CTLs that will bind to infected MHC class I presenting cells and release cytotoxic proteins that lead to death of the infected cell (E.g. Perforins and Granzymes)

Answer 48

**Top then bottom:** CD4+ cells Viral Load **Interpretation:** HIV Viral load is dependent on CD4+ number The higher the CD4+ the better the body can control viral replication and hence lower viral load

Answer 49

Shows that long term survivors of HIV (on the left) have a consistently higher level of CD8+ cells which combat the HIV infected cells In patients which cannot control the virus the CD8+ cells drop rapidly and viral load rises quickly

Answer 50

**TH-1 cells which activate CD8+ cells also activate:** B cells: * - Produces antibodies* * - Leads to opsonisation, neutralisation, complement activation* Macrophages: * - Phagocytic activity* * - Kills opsonised microbes*

Answer 51

**Primary** Antibodies are largely pentameric IgM and small amount of IgG IgM contributes to opsonisation Reflects naivety to the pathogen **Secondary:** Antibodies are largely IgG with some IgM IgG is a more effective antibody, it opsonises, activates complement and initiates antibody dependent cell cytotoxicity Larger total amount of antibody Reflects a learned response to pathogen, high amount of specific IgG

Answer 52

**TH-2 Cells activate:** Eosinophils - Killing of parasites B Cells - Release antibodies Mast Cells - Mediate local inflammation, can trigger allergic reaction **TH-17 Cells activate:** Neutrophils - Phagocytosis of bacteria

Answer 53

**IgG4:** Opsonisation **IgG, IgE:** Antibody dependent cell cytotoxicity **IgE specifically:** Mediation of allergic reaction

Answer 54

**Vaccination** **Ig Therapy:** Treatment of immune deficiency **Immediate protection:** Passive immunisation (antibody transfer) **Antibody based diagnostic testing:** Infectious disease Autoimmune disease Blood type and HLA typing

Infection 5 Flashcards

(78 cards)