Midterm 2 (Lectures 7-11)

Question 1

The immune system is composed of…?

Answer 1

• Lymphatic vessels
• Lymphatic cells
• Lymphoid tissues/organs

Question 2

Different types of immune cells screen the tissues of the body for __________________.

Answer 2

Foreign antigens

Question 3

Leukocytes are also known as…?

Answer 3

White Blood Cells (WBC)

Question 4

Where do all leukocytes arise from?

Answer 4

Bone marrow hematopoietic stem cells

Question 5

What are the primary lymphoid organs?

Answer 5

• Where immune cells develop:
• Bone marrow
• Thymus

Question 6

What are the secondary lymphoid organs?

Answer 6

• Where immune cells become activated:
• Lymph nodes
• Spleen
• Tonsils
• Mucosa-associated lymphoid tissue (MALT)

Question 7

What is MALT?

Answer 7

Mucosa-associated lymphoid tissue

Question 8

What are the 2 branches of the immune system?

Answer 8

1. Innate Immunity
2. Adaptive (Acquired) Immunity

Question 9

What is innate immunity?

Answer 9

Structures, chemicals, and processes that work to prevent pathogens from entering the body.

Question 10

What are the 4 types of innate immunity?

Answer 10

1. Physical barriers and associated chemicals (skin, mucous membranes, and microbiome)
2. Non-specific chemical defences (complement factors, cytokines = interferons)
3. Phagocytic & non-phagocytic killing of pathogens
4. Inflammation

Question 11

What forms the body’s 1st line of defence?

Answer 11

• Skin
• Mucous membranes
• Microbiome

Question 12

The skin is a _____-layered organ.

Answer 12

• Multi-layered organ
• Covered with dead cells, making an impenetrable barrier for pathogens

Question 13

Describe how the skin is a physical barrier to pathogens.

Answer 13

• Covered with dead cells = impenetrable barrier
• Perspiration secreted by sweat glands (salt, antimicrobial peptides, lysozyme)
• Sebum secreted by sebaceous/oil glands (lowers skin pH to inhibitory level)
• Secretion of small antimicrobial peptides (disrupt pathogens’ cytoplasmic membrane)

Question 14

Lysozyme destroys…?

Answer 14

The cell wall of bacteria.

Question 15

_______ helps keep the skin pliable, therefore it is less likely to break or tear.

Answer 15

Sebum

Question 16

What are the 2 distinct layers of mucous membranes?

Answer 16

1. Epithelium
2. Lamina propria

Question 17

Describe the epithelium of mucous membranes and its role in preventing pathogen entry.

Answer 17

• Epithelium = thin outer covering of the mucous membranes:
• Tightly packed epithelial cells (prevent entry)
• Covered with layer of mucus (prevent entry)
• Continual shedding of cells carries away microorganisms
• Goblet and ciliated columnar cells help remove invaders

Question 18

What type of cells found in the epithelium of mucous membranes help remove invaders?

Answer 18

• Goblet cells
• Ciliated columnar cells

Question 19

Continual shedding of _________ cells carries away microorganisms.

Answer 19

Epithelium (of mucous membranes)

Question 20

What is the lamina propria? What does it contain?

Answer 20

• Deeper connective layer that supports the epithelium of mucous membranes
• Contains connective tissue, blood vessels, nerves, and large number of immune cells

Question 21

Mucous membranes also produce ________ with antimicrobial properties.

Answer 21

Chemicals

Question 22

What physical barrier to pathogens produces and drains tears?

Answer 22

Lacrimal apparatus

Question 23

Describe the role of the lacrimal apparatus in being a physical barrier to pathogens.

Answer 23

• Produces and drains tears
• Blinking spreads tears and washes eye surface
• Lysozyme in tears destroys bacterial cell wall

Question 24

What enzyme is found in tears that destroys the bacterial cell wall?

Answer 24

Lysozyme

Question 25

What is microbial antagonism?

Answer 25

How the normal microbiome competes with potential pathogens.

Question 26

How is the microbiome a physical barrier to pathogens?

Answer 26

- Microbial antagonism: - Consumption of nutrients - Create unfavourable environment to other microorganisms - Prevent pathogen attachment to host cells - Help stimulate body's 2nd line of defence - Generate antimicrobial compounds - Provide vitamins to host (promote overall health)

Question 27

The complement system is composed of over ___ proteins, known as ______________, which are present in blood and tissues.

Answer 27

- Over 30 proteins - Complement factors

Question 28

Many complement factors are produced as...?

Answer 28

- Zygomens (inactive enzymes) - Get cleaved to be activated

Question 29

What are the 3 pathways of complement activation?

Answer 29

1. Classical pathway 2. Alternative pathway 3. Lectin pathway

Question 30

Activation of the complement system is triggered by the presence of...?

Answer 30

Pathogens in blood and tissues.

Question 31

What antimicrobial responses does activation of the complement system trigger? Describe them.

Answer 31

- Direct cytolysis = killing of pathogen (membrane attack complex) - Opsonization = coating pathogen cells to induce their phagocytosis - Inflammation = recruitment of immune cells and antimicrobial processes to the site of infection

Question 32

What are cytokines?

Answer 32

- Soluble regulatory proteins that act as intracellular signals for immune cells - Produced in response to infection - Regulate function of immune cells

Question 33

Complex web of signals among cells of the immune system.

Answer 33

Cytokine network

Question 34

What are the different types of cytokines?

Answer 34

- Interleukins (IL) - Interferons (IFN) - Growth factors - Tumor necrosis factors (TNF) - Chemokines

Question 35

Signals among leukocytes.

Answer 35

Interleukins

Question 36

Antiviral proteins that may act as cytokines.

Answer 36

Interferons

Question 37

Proteins that stimulate stem cells to divide.

Answer 37

Growth factors

Question 38

Describe TNFs.

Answer 38

- Tumor necrosis factors: - Secreted by macrophages and T cells - Kill tumour cells - Regulate immune responses & inflammation

Question 39

What are chemokines?

Answer 39

Chemotactic cytokines that signal leukocytes to move (chemotaxis).

Question 40

____________ are released by host cells to inhibit the spread of viral infections.

Answer 40

Interferons

Question 41

What are the 2 types of interferons?

Answer 41

1. Type I = IFN-alpha and IFN-beta 2. Type II = IFN-gamma

Question 42

How do Type I interferons provide uninfected neighbouring cells with resistance to viral infection?

Answer 42

- Induce expression of genes that code for antiviral proteins in cells - The antiviral proteins are activated if the cell gets infected (degrade mRNA, bind to ribosomes)

Question 43

What immune cells are granulocytes?

Answer 43

- Neutrophils - Eosinophils - Basophils

Question 44

What are some characteristics of granulocytes?

Answer 44

- Contain large granules in their cytoplasm - Have a multi-lobed nucleus

Question 45

What dye are basophils stained with? What colour do they stain?

Answer 45

- Methylene blue (basic dye) - Stain blue

Question 46

What dye are eosinophils stained with? What colour do they stain?

Answer 46

- Eosin (acidic dye) - Stain red/orange

Question 47

What dyes are neutrophils stained with? What colour do they stain?

Answer 47

- Mix of acidic/basic dyes - Stain lilac

Question 48

What are the most abundant type of leukocyte in the blood?

Answer 48

Neutrophils

Question 49

What are some characteristics of neutrophils?

Answer 49

- Phagocytic cells - Capable of diapedesis = migrate out of blood vessels into the tissues

Question 50

Leukocytes that do not have granules in their cytoplasm.

Answer 50

Agranulocytes

Question 51

Cytoplasm appears uniform under a light microscope.

Answer 51

Agranulocytes

Question 52

What immune cells are agranulocytes?

Answer 52

- Lymphocytes (T cells, B cells, NK cells) - Monocytes (macrophages)

Question 53

What are the types of lymphocytes?

Answer 53

- T cells & B cells => adaptive immunity - Natural Killer (NK) cells => innate immunity

Question 54

Describe monocytes.

Answer 54

- Migrate from the blood into tissues => mature into macrophages - Macrophages = phagocytic cells

Question 55

Neutrophils compromise ___% of total WBCs.

Answer 55

40-60%

Question 56

Lymphocytes compromise ___% of total WBCs.

Answer 56

20-40%

Question 57

Monocytes compromise ___% of total WBCs.

Answer 57

2-8%

Question 58

Eosinophils compromise ___% of total WBCs.

Answer 58

1-4%

Question 59

Basophils compromise ___% of total WBCs.

Answer 59

0.5-1%

Question 60

Rank the WBCs from most abundant to least abundant.

Answer 60

1. Neutrophils 2. Lymphocytes 3. Monocytes 4. Eosinophils 5. Basophils

Question 61

When do frequencies of leukocytes in the blood change?

Answer 61

During an infection.

Question 62

Why is a differential WBC count performed?

Answer 62

To determine the relative frequencies of different leukocytes in the blood, which can signal disease.

Question 63

Increased eosinophils indicate...?

Answer 63

- Allergies - Parasitic worm infection

Question 64

Bacterial diseases show an increase in what immune cells?

Answer 64

- Leukocytes - Neutrophils

Question 65

Viral infections show an increase in what WBCs?

Answer 65

- Lymphocytes

Question 66

What are the major phagocytes in blood and tissues?

Answer 66

- Neutrophils - Macrophages

Question 67

What are the stages of phagocytosis?

Answer 67

1. Chemotaxis 2. Adhesion 3. Ingestion 4. Maturation 5. Killing 6. Elimination

Question 68

How do eosinophils attack parasitic helminths?

Answer 68

- Adhere to their surface - Secrete toxic molecules that weaken or kill the helminth

Question 69

______________ is often indicative of a helminth infestation or allergies.

Answer 69

Eosinophilia (increased numbers in blood)

Question 70

Describe killing of pathogens by NK lymphocytes.

Answer 70

Secrete toxic molecules onto surface of virally infected cells and tumours to induce apoptosis.

Question 71

Describe non-phagocytic killing of pathogens by neutrophils.

Answer 71

- Produce toxic chemicals that kill nearby invaders - Generate neutrophil extracellular traps (NETs) that bind to and kill bacteria

Question 72

What are NETs?

Answer 72

- Neutrophil extracellular traps (NETs): - Extracellular fibers that bind to and kill bacteria

Question 73

Nonspecific response to tissue damage from various causes including pathogen infection.

Answer 73

Inflammation

Question 74

Difference between local vs. systemic inflammation?

Answer 74

- Local = restricted to site of infection/injury - Systemic = involving many organs

Question 75

Local inflammation is characterized by...?

Answer 75

- Redness - Heat - Swelling - Pain

Question 76

Inflammatory characteristics (e.g., redness, pain) are due to...?

Answer 76

- Increased blood flow to the area - Vasodilation - Increased blood vessel permeability - Immune cell infiltration into the tissue

Question 77

What are the 3 main functions of inflammation?

Answer 77

1. Destroy the agent causing the injury 2. Limit the effect of the agent on the rest of the body 3. Repair and replace the damaged tissue

Question 78

What are the 2 types of inflammation?

Answer 78

1. Acute inflammation (quick, short-lived) => typically beneficial 2. Chronic inflammation (long-lasting) => can damage tissues that will cause a disease

Question 79

What are the 3 steps inflammation is induced in?

Answer 79

1. Vasodilation & increased permeability of blood vessels at the site of infection 2. Migration of WBCs into site of infection 3. Clearance of pathogen & tissue repair

Question 80

What chemicals is vasodilation and increased blood vessel permeability triggered by?

Answer 80

- Chemicals produced in injured or infected tissues: - Bradykinins - Prostoglandins - Leukotrienes - Histamines

Question 81

___________ increases blood flow to the area.

Answer 81

Vasodilation

Question 82

What does increased blood vessel permeability allow for release of?

Answer 82

- Proteins - Antibodies - Complement factors - Blood clotting proteins - Fluids

Question 83

Migration of leukocytes out of the blood vessels.

Answer 83

Extravasation

Question 84

What steps does extravasation involve?

Answer 84

1. Neutrophils & monocytes delivered to site of infection (recruited by chemokines) 2. Attach to receptors and adhesion factors on blood vessels 3. Diapedesis = squeeze between cells of vessel wall and enter site of infection

Question 85

What is diapedesis?

Answer 85

How WBCs (e.g., neutrophils, monocytes) squeeze between cells of blood vessel wall and enter the site of infection.

Question 86

What facilitates tissue repair?

Answer 86

Delivery of nutrients and oxygen.

Question 87

What are the steps of tissue repair?

Answer 87

1. Blood clot formation 2. Phagocytosis & killing of pathogens 3. Pus formation 4. Clearance of dead cells 5. Repair of damaged tissue by tissue stem cells 6. Blood clot absorption

Question 88

What is pus made up of?

Answer 88

- Damaged tissue - Dead WBCs (mostly neutrophils)

Question 89

The body's ability to recognize and defend itself against distinct invaders and their products.

Answer 89

Adaptive immunity

Question 90

What are the 5 attributes of adaptive immunity?

Answer 90

1. Specificity 2. Inducibility 3. Clonality 4. "Self" vs. "Non-Self" Discrimination 5. Memory (immunological)

Question 91

What are the 2 main types of lymphocytes involved in adaptive immunity?

Answer 91

1. B cells => humoral immune responses (antibodies) 2. T cells => cell-mediated immune responses

Question 92

What are antigens?

Answer 92

- Molecules that the body recognizes as foreign => triggers a specific immune response - Include various bacterial components, and proteins of viruses, fungi, and protozoa

Question 93

How are antigens recognized by lymphocytes?

Answer 93

Epitopes = 3D regions on antigens

Question 94

What are epitopes?

Answer 94

3D regions on antigens (small peptides) that are recognized by lymphocytes.

Question 95

What are the 3 types of antigens?

Answer 95

1. Exogenous => include components of an extracellular microbe (e.g., from cell walls, membranes, flagella, pilli, and toxins) 2. Endogenous => produced by intracellular microbes that reproduce inside a cell 3. Autoantigens => self-antigens derived from normal cellular processes

Question 96

T cells express ______________________ that recognize specific epitopes of an antigen.

Answer 96

Antigen-specific receptors

Question 97

Describe the structure of antigen-specific T cell receptors.

Answer 97

- Composed of 2 protein chains (dimer) that are embedded in the cell membrane - Each chain composed of 2 domains: variable and constant regions - AA of the variable region vary between different T cells = each T cell has different antigen specificity

Question 98

What are the different types of T cells based on?

Answer 98

- Surface glycoproteins - Characteristic functions

Question 99

What are the 3 types of T cells?

Answer 99

1. Cytotoxic T cells = CD8+ (directly kills other cells) 2. Helper T cells = CD4+ (help regulate B cells and cytotoxic T cells) 2. Regulatory T cells = CD4+ (represses adaptive immune responses as they can cause damage to tissues if active for too long)

Question 100

What are some different types of Helper T cells?

Answer 100

- Depending on type of cytokine they produce: - TH1 - TH2 - TH17

Question 101

T cells only recognize antigens that are processed and presented to them on...?

Answer 101

Major histocompatibility complexes (MHC) = glycoproteins found on most cells.

Question 102

T cells receptors only bind epitopes associated with an ______ protein.

Answer 102

MHC (major histocompatibility complexes)

Question 103

Only specific cells called ___________ can process and present antigens to activate T cells.

Answer 103

- Antigen-presenting cells (APC) => e.g., dendritic cells - Expand/increase SA so they can express antigens

Question 104

What are the 2 classes of MHC proteins?

Answer 104

1. MHC class I = present on all cells except RBCs 2. MHC class II = present on antigen-presenting cells

Question 105

CD8+ (cytotoxic) T cells recognize antigens presented on...?

Answer 105

MHC-I molecules

Question 106

CD4+ (helper) T cells recognize antigens presented on...?

Answer 106

MHC-II molecules

Question 107

How are endogenous antigens processed? What type of MHC are they present on?

Answer 107

- Processed by the cell's proteosome complex => sent to ER => packaged by Golgi bodies into vesicles => vesicle fuses with cell membrane - Presented on MHC-I molecules

Question 108

How are exogenous antigens processed? What type of MHC are they present on?

Answer 108

- Are phagocytosed and processed in the endosomal compartment - Presented on MHC-II molecules

Question 109

Describe the cell-mediated immune response.

Answer 109

- Mediated by CD8+ cytotoxic T cells - Respond to intracellular pathogens (viruses) and abnormal body cells (cancer cells) - T cell activation occurs in the 2ndary lymphoid organs (lymph nodes, spleen, MALT)

Question 110

T cell activation occurs in what types of organs?

Answer 110

2ndary lymphoid organs (lymph nodes, spleen, MALT).

Question 111

Describe the steps to cytotoxic T cell (CTL) activation.

Answer 111

1. Antigen presentation: an infected or antigen-presenting cell (APC) displays a foreign antigen on its MHC-I molecule, signalling Tc cells 2. Helper T cell differentiation: Th cells, activated by MHC-II on APCs, release cytokines like IL-2 (interleukin 2) to enhance Tc cell activation (have IL-2 receptors) 3. Clonal expansion: active Tc cells rapidly proliferate and differentiate, killing infected cells 4. Self-stimulation: Tc cells produce their own IL-2, activating even more Tc cells => takes about 1-2 weeks to mount effective immune response

Question 112

Describe the 2 pathways that cytotoxic T cells can kill targets through.

Answer 112

1. Perforin-granzyme pathway: perforin forms pores in the cell membrane => allows granzymes to enter the cell and induce apoptosis 2. CD95 pathway: mediated through cell receptors that induce apoptosis in the target cell

Question 113

B cells are found primarily in...?

Answer 113

- Spleen - Lymph nodes - MALT - Small % circulate in the blood

Question 114

The major function of B cells is secretion of...?

Answer 114

Secretion of antibodies (immunoglobulin).

Question 115

Describe the structure of antibodies (immunoglobulins).

Answer 115

- Y-shaped structure: - Made up of 2 heavy (H) and 2 light (L) protein chains - Each protein chain is composed of constant and variable domains - The variable regions of the H and L chains form the antigen-binding sites

Question 116

The antigen-binding sites on B cells are formed by...?

Answer 116

The variable regions of H/L chains.

Question 117

What do B cells express for antigen recognition?

Answer 117

- Antigen-specific B cell receptor (BCR) - BCRs on each B cell recognize a specific epitope

Question 118

BCRs (B cell receptors) are _________ forms of immunoglobulins.

Answer 118

Membrane-bound

Question 119

Humoral immunity is also called...?

Answer 119

T-dependent humoral immunity (depends on the function of helper T cells)

Question 120

What are the 4 steps of activation of humoral immune response?

Answer 120

1. Antigen presentation for CD4+ T cell activation 2. Differentiation of CD4+ T cells into Helper T cells 3. Activation of B cells 4. Proliferation and differentiation of B cells into antibody-producing plasma cells

Question 121

What are the functions of antibodies?

Answer 121

- Complement factor activation (through classical pathway) & inflammation - Neutralization (prevent antigen from attaching to cell receptors) - Opsonization (coating of antigens with antibody molecules recognized by phagocytes) - Agglutination (clumping of pathogens due to antibodies binding) - Antibody-dependent cellular cytotoxicity (ADCC; NK cells have receptors that recognize the antibody)

Question 122

What are the 5 classes of antibodies?

Answer 122

1. IgM 2. IgG 3. IgA 4. IgE 5. IgD

Question 123

Describe IgM antibodies.

Answer 123

- Monomer or Pentamer - Produced early on - Monomer can act as BCR - Pentamer involved in complement activation, neutralization, and agglutination

Question 124

What type of antibody is most abundant?

Answer 124

IgG

Question 125

Describe IgG antibodies.

Answer 125

- Monomer - Most abundant antibody - Involved in all antibody functions (complement activation, neutralization, opsonization, agglutination, ADCC), and oxidation

Question 126

Describe IgA antibodies.

Answer 126

- Monomer or Dimer - Dimer secreted on surface of mucous membranes - Involved in neutralization and agglutination

Question 127

Describe IgE antibodies.

Answer 127

- Monomer - Involved in allergic reactions

Question 128

Describe IgD antibodies.

Answer 128

- Monomer - Unknown function, perhaps acts as BCR

Question 129

The majority of T and B cells are _______(short/long)-lived.

Answer 129

Short-lived (die within a few days of activation)

Question 130

Describe memory T and B cells.

Answer 130

- Long-lived (persist for months or years in lymphoid tissues) - Respond to subsequent antigen exposure much FASTER than the primary response - Memory (2ndary) response is more effective than the primary response

Question 131

Primary/secondary response is more effective.

Answer 131

Secondary (memory => quicker, stronger)

Question 132

Specific immunity acquired during an individual's life.

Answer 132

Acquired immunity

Question 133

What are the 2 types of acquired immunity?

Answer 133

1. Naturally acquired: response against antigens encountered in daily life 2. Artificially acquired: response to antigens introduced via a vaccine

Question 134

What are the 2 artificial methods of immunity?

Answer 134

1. Active immunization: administration of antigens so patient actively mounts an adaptive immune response (i.e. vaccination) 2. Passive immunotherapy: individual acquires immunity through the transfer of antibodies formed by immune individual or animal

Question 135

The most efficient, cost-effective, and safe method of controlling infectious diseases.

Answer 135

Vaccination

Question 136

__________ are a method of inducing immunity without causing the disease.

Answer 136

Vaccines

Question 137

After vaccination, and subsequent exposure to the pathogen, what happens?

Answer 137

The memory B and T cells mount a strong immune response, preventing the pathogen from causing a disease.

Question 138

What does a vaccine contain?

Answer 138

- Antigens - Weakened or killed pathogen - Or parts of the pathogen

Question 139

What are some side effects of vaccination?

Answer 139

- Mild local inflammation resulting in pain, fever, fatigue - May trigger allergic reactions or anaphylactic shock in some individuals - Residual virulence from attenuated viruses

Question 140

What are the 2 types of vaccines that contain whole pathogens called?

Answer 140

1. Attenuated (modified live) vaccines 2. Inactivated (killed) vaccines

Question 141

What are the 2 types of vaccines that contain parts of the pathogen called?

Answer 141

1. Subunit vaccines 2. Toxoid (inactivated toxin) vaccines

Question 142

What are the 2 types of vaccines that are made using recombinant DNA technology?

Answer 142

1. RNA and DNA vaccines 2. Recombinant vector vaccines

Question 143

The process of treating a pathogen to make it less virulent.

Answer 143

Attenuation

Question 144

What are some examples of attenuated vaccines?

Answer 144

- MMRV (Measles, Mumps, Rubella, Varicella) - Sabin (Oral Polio)

Question 145

What are some advantages of attenuated vaccines?

Answer 145

- Mimic the pathogen, resulting in mild infection = stimulate a strong immune response - Contain a large number of antigens - Can induce life-long immunity

Question 146

What are some disadvantages of attenuated vaccines?

Answer 146

- Can cause disease in immunocompromised individuals (b/c can retain residual virulence) - Not suitable for pregnant women (risk of harm to the developing fetus) - Risk of the pathogen reverting to virulent form

Question 147

Vaccine that contains killed whole pathogen.

Answer 147

Inactivated vaccines

Question 148

What are some examples of inactivated (killed) vaccines?

Answer 148

- Salk (inactivated Polio) - Seasonal Flu vaccines

Question 149

What are some advantages of inactivated vaccines?

Answer 149

- Safer than attenuated live vaccines - Contains large number of antigens

Question 150

What are some disadvantages of inactivated vaccines?

Answer 150

- Antigenically weaker; therefore administered at higher doses - May require booster dose to achieve full immunity

Question 151

Vaccines that contain antigenic fragments of microbes instead of whole pathogen.

Answer 151

Subunit vaccines

Question 152

What is an example of a subunit vaccine?

Answer 152

Hepatitis B vaccine

Question 153

What is an advantage of subunit vaccines?

Answer 153

Safe (no infectious agent present)

Question 154

What are some disadvantages of subunit vaccines?

Answer 154

- Often require multiple doses to achieve full immunity - Often contain adjuvants (chemicals added to increase antigenicity) that cause local inflammation

Question 155

Chemicals added to (subunit/toxoid) vaccines to increase effective antigenicity.

Answer 155

Adjuvants

Question 156

Chemically or thermally modified toxins used to stimulate active immunity.

Answer 156

Toxoid vaccines

Question 157

Describe toxoid vaccines.

Answer 157

- Inactivated toxins (chemically or thermally modified) used to stimulate active immunity - Useful for some bacterial diseases: diphtheria, tetanus, whooping cough - Stimulate antibody-mediated immunity

Question 158

What type of vaccine is useful for bacterial diseases and stimulates antibody-mediated immunity?

Answer 158

Toxoid vaccines

Question 159

What are some disadvantages of toxoid vaccines?

Answer 159

- Require multiple doses (toxoids possess few antigenic determinants) - May contain adjuvants (cause local inflammation)

Question 160

What is an advantage of toxoid vaccines?

Answer 160

High safety profile

Question 161

Vaccine that involves simultaneous administration of antigens from several pathogens.

Answer 161

Combination vaccines

Question 162

What is an example of a combination vaccine?

Answer 162

DTaP (Diphtheria; Tetanus; Pertussis)

Question 163

Vaccine that combines bacterial capsule polysaccharide (not very antigenic) with a highly antigenic protein.

Answer 163

Conjugate vaccines

Question 164

Conjugate vaccines induce a strong ________ immunity against polysaccharide capsules.

Answer 164

Humoral (antibody) immunity

Question 165

There are conjugate vaccines against which bacteria?

Answer 165

- Haemophilus influenzae - Streptococcus pneumoniae

Question 166

Attempts to make vaccines more effective, cheaper, and safer.

Answer 166

- Recombinant vector vaccine - mRNA vaccine

Question 167

Future generation of vaccines.

Answer 167

Peptide vaccines

Question 168

Administration of antiserum that contained pre-formed antibodies.

Answer 168

Passive immunization

Question 169

What is an advantage of passive immunization?

Answer 169

Provides immediate protection against a recent infection or ongoing disease.

Question 170

What are the limitations to antiserum (passive immunization)?

Answer 170

- Can trigger allergic reactions (serum sickness) - Antibodies of antiserum are degraded relatively quickly - Individuals NOT protected from subsequent infections

Question 171

How are limitations of antiserum (passive immunization) overcome?

Answer 171

Development of hybridomas (immortalized antibody-producing plasma cells).

Question 172

Immortalized antibody-producing plasma cells.

Answer 172

Hybridomas

Question 173

Describe hybridomas (immortalized antibody-producing plasma cells).

Answer 173

- Produce monoclonal antibodies with defined antigen specificities - High purity of antibodies - Free of serum component (does NOT trigger allergic reactions)

Question 174

What are the different types of serological tests?

Answer 174

- Precipitation tests - Agglutination tests - Neutralization tests - Complement fixation tests - Labelled antibody tests - Point-of-care tests

Question 175

What is serology?

Answer 175

The determination of the presence of specific antigens or antibodies in serum.

Question 176

Describe precipitation tests.

Answer 176

- Antigens and antibody mixed in the proper proportion form antigen-antibody complexes (immune complexes) - Immune complexes form a precipitate - Immunodiffusion performed in a semi-solid gel is a common precipitation technique

Question 177

What immune complexes?

Answer 177

Antigen-antibody complexes ("1:1 ratio") that form a precipitate.

Question 178

Agglutination occurs due to the...?

Answer 178

Cross-linking of antibodies with particulate antigens.

Question 179

Clumping of insoluble particles.

Answer 179

Agglutination

Question 180

Aggregation of soluble molecules.

Answer 180

Precipitation

Question 181

Agglutination of RBCs.

Answer 181

Hemagglutination

Question 182

Hemagglutination can be used to determine ____________.

Answer 182

Blood type

Question 183

Describe agglutination tests (titration).

Answer 183

- Method to measure antibody levels in blood serum - Serum being tested is serially diluted and tested for agglutinating activity - Highest dilution of serum giving a positive reaction is the titer

Question 184

The use of agglutination to quantify the amount of antibody in a serum sample.

Answer 184

Titration

Question 185

Describe viral neutralization.

Answer 185

- Cytopathic effect: viruses introduced into appropriate cell cultures will kill the cells - Ability of virus to kill culture cells is neutralized when virus is first mixed with antibodies against it

Question 186

Detects presence of viral neutralizing antibodies in the serum.

Answer 186

Viral neutralization test

Question 187

Describe the viral neutralization test.

Answer 187

- Mixture of virus and serum added to cell culture - Absence of cytopathic effect indicates presence of antibodies against the virus in the serum - Identifies whether individual exposed to a particular virus

Question 188

Describe the viral hemagglutination inhibition test.

Answer 188

- Useful for viruses that are NOT cytopathic - Based on viral hemagglutination (some viral surface proteins can clump RBCs) - A serum sample that contains antibodies against a specific virus will inhibit viral hemagglutination - Commonly used to detect antibodies against influenza, measles, and mumps

Question 189

What serological test is commonly used to detect antibodies against influenza, measles, and mumps?

Answer 189

Viral hemagglutination inhibition test (type of neutralization test)

Question 190

What are the types of labelled antibody tests?

Answer 190

- Indirect/direct fluorescent antibody test - ELISA (EIA) - Antibody sandwich ELISA - Western blot (immunoblot)

Question 191

Describe labelled antibody tests.

Answer 191

- Use antibody molecules linked to some "label" that enables them to be easily detected - Used to detect either antigens or antibodies

Question 192

What serological test uses antibodies labelled with fluorescent dye?

Answer 192

Fluorescent antibody tests

Question 193

What are the differences between direct and indirect fluorescent antibody tests?

Answer 193

- Direct: the label is on the primary antibody - Indirect: the label is on the secondary antibody (anti-antibody)

Question 194

What is ELISA or EIA?

Answer 194

- ELISA = enzyme-linked immunosorbent assay - EIA = enzyme immunoassay

Question 195

Describe the ELISA antibody test.

Answer 195

- Uses an enzyme as the label (enzyme-linked anti-antibody) - Reaction of enzyme with its substrate produces a coloured product indicating a positive test

Question 196

What are some advantages of the ELISA antibody test?

Answer 196

- Can detect either antibody or antigen - Sensitive - Quantitative - Easy to perform/automate - Relatively inexpensive

Question 197

Describe the antibody sandwich ELISA.

Answer 197

- Modification of the ELISA technique - Commonly used to detect antigen - Antigen being tested for is "sandwiched" between 2 antibody molecules

Question 198

Describe Western blotting.

Answer 198

- Technique to detect antibodies against multiple antigens - Used to confirm the presence of proteins

Question 199

What are the 3 steps to Western blotting?

Answer 199

1. Electrophoresis separates proteins in a solution 2. Blotting transfers protein to nitrocellulose membrane 3. Probe the membrane with antibodies and detect colour where antibody has bound to proteins

Question 200

What are some common point-of-care serological tests?

Answer 200

- Immunofiltration assay - Immunochromatography assay

Question 201

What are point-of-care serological tests?

Answer 201

- Simple immunoassays that give results in minutes - Useful in determining a quick diagnosis

Question 202

Describe an immunofiltration assay.

Answer 202

- Rapid ELISA that uses antibodies bound to membrane filters rather than plates - Reduced time (due to the large SA of the membrane filter) to complete the assay

Question 203

Describe immunochromatography.

Answer 203

- Very rapid and easy-to-read ELISAs - Antigen solution flows through a porous strip and encounters labelled antibody - Visible line produced when antigen-antibody immune complexes encounter antibody against them - Used in pregnancy testing and for identification of some infections

Question 204

Used in pregnancy testing.

Answer 204

Immunochromatography

Question 205

Allergies (hypersensitivity) are immune responses against __________.

Answer 205

Allergens (harmless antigens)

Question 206

Caused by immune responses against self-antigens.

Answer 206

Autoimmune disorders

Question 207

What are some examples of autoimmune disorders?

Answer 207

- Autoimmune hemolytic anemia (antibodies against RBC) - Type 1 diabetes mellitus (cellular damage to islets of Langerhans) - Multiple sclerosis (cellular damage to myelin sheaths)

Question 208

What are the 2 types of immunodeficiencies?

Answer 208

1. Primary: genetic defects that impair immune functions 2. Secondary: caused by infections, therapies, aging, malnutrition, etc.

Question 209

AIDS

Answer 209

Acquired immunodeficiency syndrome

Question 210

HIV

Answer 210

Human immunodeficiency virus

Question 211

What are the signs and symptoms of AIDS?

Answer 211

- Severe decrease in Helper (CD4+) T cells; < 200 cells/uL blood - Seroconversion (presence of serum antibodies against HIV) - Several opportunistic or rare infections along with HIV infection

Question 212

Presence of serum antibodies against HIV.

Answer 212

Seroconversion

Question 213

Describe HIV infection.

Answer 213

- HIV = enveloped +ssRNA retrovirus - HIV infects Helper (CD4+) T cells; CD4 is the receptor for HIV gp120 protein - CD4 binding to gp120 mediates attachment/entry of HIV into Helper T cells

Question 214

CD4 is the receptor for HIV _____ protein.

Answer 214

gp120

Question 215

What are the 2 major types of HIV?

Answer 215

1. HIV-1: prevalent across the globe 2. HIV-2: mainly present in parts of West Africa

Question 216

Describe the replication cycle of HIV.

Answer 216

1. Attachment 2. Entry by endocytosis 3. Uncoating 4. Synthesis of DNA (reverse transcriptase: ssRNA to dsDNA) 5. Integration of viral genome into human DNA 6. Synthesis of ssRNA and polypeptides 7. Release 8. Assembly and maturation (protease function)

Question 217

Describe the pathogenesis of HIV.

Answer 217

1. Primary infection (HIV in blood, decreased Helper T cell count) 2. Clinical latency (increased antibodies against HIV) 3. Opportunistic diseases 4. Death (Helper T cell count = 0)

Question 218

What are the modes of HIV transmission?

Answer 218

- Sexual contact with an infected (HIV+) individual - Intravenous drug use (sharing of contaminated needles) - Blood transfusion/organ transplant (if donor is HIV+) - Mother-to-child transmission (from an HIV+ mother to child)

Question 219

Describe the diagnosis of HIV infection.

Answer 219

- Unexplained weight loss, fatigue, fever; and other signs/symptoms of opportunistic infections - < 200 Helper (CD4+) T cells/uL blood - Seroconversion (presence of serum antibodies against HIV) - PCR test for HIV RNA (definitive diagnosis)

Question 220

Describe HAART (highly active anti-retroviral therapy).

Answer 220

- Cocktail of 3 or more antiviral drugs (nucleotide analogs, integrase inhibitors, protease inhibitors, reverse transcriptase inhibitors); combination therapy important to prevent drug resistance - Stops HIV replication (reduces viral titers & prevents CD4+ T cell destruction) - Treatment immediately after diagnosis of HIV infection significantly reduces the chance of developing AIDS

Question 221

HAART

Answer 221

Highly active anti-retroviral therapy

Question 222

There are NO vaccines for _____.

Answer 222

HIV

Question 223

Skin is a ______________ membrane.

Answer 223

Cutaneous

Question 224

What are the 2 distinct layers of the skin?

Answer 224

1. Epidermis (outer) 2. Dermis (inner)

Question 225

What are some functions of the skin?

Answer 225

- Prevents excessive water loss - Regulates temperature - Assists in vitamin D formations - Involved in sensory phenomena - Barrier against microbial invaders

Question 226

Describe some characteristics of the skin microbiome.

Answer 226

- Normally harmless microbes - Typically grow in moist areas of the skin - Compete with potential pathogens for nutrients and space - Produce chemicals that interfere with growth of other microbes - Cannot be completely removed through cleansing - Waste products cause body odor

Question 227

Some ________ and ___________ tolerate the harsh environment of the epidermis.

Answer 227

- Yeasts - Bacteria

Question 228

What are some microbes that make up the skin microbiome?

Answer 228

- Yeast (Malassezia) - Gram-positive bacteria (Staphylococcus epidermidis, Micrococcus, Diphtheroids like Cutibacterium acnes)

Question 229

Small lipophilic yeast that digests sebum.

Answer 229

Malassezia

Question 230

How may pathogenic microbes produce disease of the skin?

Answer 230

- Penetrate epidermis due to trauma (cuts, scrapes, surgery, burns, bites, etc.) - Or if immune system compromised

Question 231

What skin diseases does Staphylococcus aureus cause?

Answer 231

- Folliculitis - Scalded disease syndrome - Impetigo

Question 232

What skin diseases does Streptococcus pyogenes cause?

Answer 232

- Erysipelas - Cellulitis - Necrotising fasciitis

Question 233

Acne is caused by what bacteria?

Answer 233

Cutibacterium acnes

Question 234

Cat scratch disease is caused by what bacteria?

Answer 234

Bartonella henselae

Question 235

Pseudomonas infection is caused by what bacteria?

Answer 235

Pseudomona aeruginosa

Question 236

Spotted fever rickettsiosis is caused by what bacteria?

Answer 236

Rickettsia rickettsii

Question 237

Cutaneous anthrax is caused by what bacteria?

Answer 237

Bacillus anthracis

Question 238

Gas gangrene is caused by what bacteria?

Answer 238

Clostridium perfringens

Question 239

What are signs and symptoms of folliculitis?

Answer 239

- Infection of the hair follicle; becomes red, swollen, pus-filled (often called a pimple) - Called a sty when it occurs at the eyelid base - Spread of infection into surrounding tissues can produce a furuncle (boil); large, painful, raised nodular - Carbuncles occur when multiple furuncles grow together

Question 240

Spread of folliculitis into surrounding tissues produces this.

Answer 240

Furuncle (large, painful, raised nodular)

Question 241

_________ occur when multiple furuncles grow together.

Answer 241

Carbuncles

Question 242

Folliculitis is most commonly caused by what bacteria (2 common species)? Describe their characteristics.

Answer 242

- Most commonly caused by Staphylococcus - 2 common species in skin are S. epidermidis and S. aureus (normal microflora than can become pathogenic) => Gram-positive; facultatively anaerobic; cocci typically arranged in clusters; tolerant of salt and desiccation

Question 243

What are the virulence factors that S. aureus (involved in folliculitis) produces?

Answer 243

- Coagulase (blood clotting) - Hyaluronidase (breaks down HA in tissues) - Staphylokinase (dissolves blood clot) - Lipase (digests lipids; including sebum) - β-lactamase (resistance to penicillins) - Polysaccharide slime layer & Protein A (on cell surface); inhibits phagocytosis - Cytolytic toxins (disrupts cell membrane) - Leukocidin (kills leukocytes) - Epidermal cell differentiation inhibitor (disrupts lining of blood vessels) - Exfoliating / toxic shock syndrome toxins (in more virulent strains of S. aureus)

Question 244

Staphylococcus epidermidis lacks ________________ and is rarely pathogenic.

Answer 244

Lacks virulence factors

Question 245

Describe the pathogenesis of folliculitis.

Answer 245

- Staphylococcus transmitted via direct contact or by fomites - Infection can spread to hypodermis (furuncle), neighbouring hair follicles (carbuncle), into the blood (bacteremia), and other organs

Question 246

Describe the epidemiology of folliculitis.

Answer 246

- S. epidermidis lacks virulence factors and is rarely pathogenic - S. aureus transiently colonizes the skin or mucous membranes of most people

Question 247

Describe the diagnosis of folliculitis.

Answer 247

Isolation of Gram-positive bacteria in grape-like clusters from pus that can clot blood (diagnostic of S. aureus infection).

Question 248

Describe the treatment for folliculitis.

Answer 248

- Treated with topical/oral semi-synthetic penicillin - Or vancomycin (for resistant strains)

Question 249

What is the prevention for folliculitis?

Answer 249

Hand antisepsis; proper procedures in hospitals to minimize methicillin-resistant S. aureus (MRSA) infections.

Question 250

What are the signs and symptoms of Staphylococcal scalded skin syndrome (SSSS)?

Answer 250

- Cells of the epidermis separate from one another and from the underlying tissue - Skin becomes red and wrinkled; forms blisters filled with clear liquid (NOT pus) - Outer epidermis peels off in sheets

Question 251

Describe the pathogens/virulence factors involved in SSSS.

Answer 251

- Caused by some Staphylococcus aureus strains - 1 or 2 different exfoliative toxins; causes dissociation of epidermal desmosomes (intracellular bridge proteins that hold together cytoplasmic membranes of adjacent cells)

Question 252

Intracellular bridge proteins that hold together cytoplasmic membranes of adjacent cells.

Answer 252

Desmosomes

Question 253

Describe the pathogenesis of SSSS.

Answer 253

- Circulation of toxins in the blood produces toxemia - NO scarring (dermis is unaffected); epidermis is restored within 7-10 days after infection is resolved - Death is rare but most often due to 2ndary infections by Candida albicans or Pseudomona aeruginosa

Question 254

Death by SSSS is rare but most often due to 2ndary infections by...?

Answer 254

- Candida albicans - Pseudomona aeruginosa

Question 255

Describe the epidemiology of SSSS.

Answer 255

- Disease occurs primarily in infants and young children - Can affect elderly and immunocompromised patients - Transmitted by person-to-person spread of bacteria (need cut/tear in skin, etc.)

Question 256

Describe the diagnosis, treatment, and prevention of SSSS.

Answer 256

- Diagnosis: by characteristic sloughing of skin - Treatment: intravenous semi-synthetic penicillin (oxacillin) - Prevention: difficult due to widespread presence of S. aureus

Question 257

What are the signs and symptoms of impetigo (pyoderma)?

Answer 257

- Red patches form on the face and limbs - Patches develop into pus-filled vesicles - Vesicles break and form a crust that causes intense itching

Question 258

What are the signs and symptoms of erysipelas?

Answer 258

- Impetigo infection spreads to the lymph nodes (triggering pain and inflammation) - Reddening occurs on the face, arms, or legs - Swollen local lymph nodes, pain, fever, chills, and leukocytosis (increased WBC counts)

Question 259

Leukocytosis refers to...?

Answer 259

Increased WBC counts

Question 260

What are the pathogens that cause impetigo and erysipelas?

Answer 260

- Staphylococcus aureus causes most cases (80%) of impetigo - Streptococcus pyogenes causes erysipelas and some cases (20%) of impetigo

Question 261

Group A Streptococcus.

Answer 261

Streptococcus pyogenes

Question 262

What are the virulence factors that Streptococcus pyogenes produces (to cause impetigo/erysipelas)?

Answer 262

- M protein (membrane protein that destabilizes complement system and interferes with phagocytosis) - Hyaluronic acid capsule (to hide from phagocytes) - Pyrogenic toxins (stimulates macrophages and T cells to release cytokines causing fever, rush, and shock)

Question 263

Describe the pathogenesis of impetigo/erysipelas.

Answer 263

- The bacteria invade where the skin is compromised - Acute glomerulonephritis if infection spreads to kidneys

Question 264

What can happen if impetigo/erysipelas infection spreads to kidneys?

Answer 264

Acute glomerulonephritis

Question 265

Describe the epidemiology of impetigo/erysipelas.

Answer 265

- Impetigo occurs mostly in children - Erysipelas occurs in children and adults - Transmitted by person-to-person contact OR via fomites (toys, clothing, bedding, towels, or hairbrush)

Question 266

Describe the diagnosis of impetigo/erysipelas.

Answer 266

- The presence of pus-filled vesicles (impetigo) - Gram-positive cocci in clusters (Staphylococcus) or chains (Streptococcus) in the pus

Question 267

Describe treatment and prevention for impetigo/erysipelas.

Answer 267

- Treatment: impetigo is treated with topical mupirocin, oral clindamycins, or doxycycline (and careful cleaning of infected areas); erysipelas is treated with penicillin - Prevention: proper hygiene and cleanliness

Question 268

Describe the signs and symptoms of necrotizing fasciitis.

Answer 268

- Heat, intense pain, swelling, and sunburn-like rash at the site of infection - Patients develop fever, nausea, malaise, and muscle ache - Infection can destroy soft tissues causing a drop in BP, possible mental confusion, and ultimately comatos

Question 269

Describe the pathogens (and their virulence factors) that cause necrotizing fasciitis.

Answer 269

- Most cases caused by Streptococcus pyogenes (streptokinase & hyaluronidase facilitate invasion of tissues; exotoxin A & streptolysin S damage cells and tissues) - Some cases are caused by Staphylococcus aureus, Clostridium perfringens, and Bacterioides fragilis

Question 270

Describe the pathogenesis of necrotizing fasciitis.

Answer 270

1. S. pyogenes is passed from person-to-person and enters the body through breaks in the skin; it spreads rapidly along muscle fascia 2. S. pyogenes secrete enzymes (streptokinases, hyaluronidase) that allow the bacterium to invade body tissues (and deoxyribonucleases: break down DNA = bacteria can spread) 3. Other virulence factors include M protein (help bacterium attach to nose/throat cells, and survive phagocytosis) 4. S. pyogenes also secretes toxins (streptolysin S, exotoxin A; triggers overactive immune response) that damage tissue

Question 271

Describe the epidemiology of necrotizing fasciitis.

Answer 271

- Transmission from person-to-person through breaks in the skin - Can develop following surgery, abortion, and insect bite - Increased risk in diabetes, cancer, and chickenpox

Question 272

Describe diagnosis and prevention of necrotizing fasciitis.

Answer 272

- Diagnosis: difficult because early symptoms are general and flu-like - Prevention: proper hygiene and cleanliness of wounds

Question 273

Describe treatment of necrotizing fasciitis.

Answer 273

- Considered surgical emergency; treated by immediate removal of dead tissue and repeated until bacterial tissue destruction is halted - Intravenous broad-spectrum antimicrobials help curb severity of the disease

Question 274

Acne is caused by bacterial infection of the ______________.

Answer 274

Hair follicles

Question 275

Describe the development of acne.

Answer 275

1. Normal skin: oily sebum produced by glands reaches the hair follicle (discharged onto the skin surface via the pore) 2. Whitehead: when bacteria infect the hair follicle, the inflamed skin swells over the pore (causes accumulation of colonizing bacteria and sebum) 3. Blackhead: dead/dying bacteria and sebum form a blockage of the pore 4. Pustule formation: caused by severe inflammation of the hair follicle (rupture, causing cystic acne; often resolved by scar tissue formation)

Question 276

Describe the pathogen that causes acne.

Answer 276

- Commonly caused by Cutibacterium acnes (Gram-positive, rod-shaped diphtheroids) - Commonly found on the skin

Question 277

Describe the epidemiology of acne.

Answer 277

- Acne bacteria are normal members of the microbiome - Typically begins in adolescence but can occur later in life

Question 278

Describe the diagnosis of acne.

Answer 278

Diagnosed by visual examination of the skin.

Question 279

Describe the treatments for acne.

Answer 279

- Antimicrobial drugs - Topical benzoyl peroxide cause exfoliation of dead skin cells - Accutane is used for severe acne; inhibits formation of sebum (can cause intestinal bleeding and birth defects) - UV light is also used to destroy bacteria

Question 280

Why is long-term use of Accutane not recommended?

Answer 280

Can cause intestinal bleeding and birth defects.

Question 281

Describe the signs and symptoms of cat scratch disease.

Answer 281

- Fever, malaise - Localized swelling at infection site

Question 282

Describe the pathogens/virulence factors involved in cat scratch disease.

Answer 282

- Caused by Bartonella henselae - Endotoxin (Lipid A of LPS) is the primary virulence factor

Question 283

Describe the epidemiology of cat scratch disease.

Answer 283

- Transmitted by cat bites/scratches - Or by blood-sucking arthropods

Question 284

Describe the diagnosis, treatment, and prevention of cat scratch disease.

Answer 284

- Diagnosis: serological test to detect Bartonella antigens - Treatment: antimicrobials (azithromycin) - Prevention: avoid or properly clean cat scratches/bites

Question 285

Describe the signs and symptoms of Pseudomonas infection.

Answer 285

- Common opportunistic infection in burn victims - Blood infection causes fever, chills, and shock - Pyocyanin (blue-green bacterial pigment) in massive infections; causes discolouration

Question 286

Describe the pathogen that causes Pseudomonas infection.

Answer 286

- Pseudomonas aeruginosa (Gram-negative bacillus) - Found in soil, decaying matter, moist environments, hospital surfaces

Question 287

What are the virulence factors that Pseudomonas aeruginosa produces?

Answer 287

- Fimbriae, adhesins (adhesion; biofilm formation) - Capsule (inhibition of phagocytosis) - Neuraminidase, elastase (attachment; tissue breakdown) - Endotoxin (triggers fever, inflammation, blood clotting) - Exotoxin A, exoenzyme S (inhibition of protein synthesis; cell death) - Pyocyanin (tissue damage via formation of reactive oxygen species)

Question 288

Describe the pathogenesis of Pseudomonas infection.

Answer 288

- P. aeruginosa is an opportunistic pathogen (cannot penetrate intact tissues and cells) - Infection can occur in burn victims; bacteria grow under the surface of the burn, kill cells, destroy tissue, and trigger shock

Question 289

Describe the epidemiology of Pseudomonas infection.

Answer 289

P. aeruginosa is an inhabitant of water and soil; can infect almost any organ or system once in the body.

Question 290

Describe the diagnosis of Pseudomonas infection.

Answer 290

- Diagnosis can be difficult - Pyocyanin discolouration indicates massive infection

Question 291

Describe treatments and prevention of Pseudomonas infection.

Answer 291

- Treatment: difficult because of multi-drug resistance; combination of antimicrobials and debridement of burns - Prevention: impossible to prevent exposure (P. aeruginosa is widespread)

Question 292

What is the most severe form of spotted fever rickettsiosis?

Answer 292

- Rocky Mountain spotted fever - Transmitted via hard ticks

Question 293

Describe the signs and symptoms of spotted fever rickettsiosis.

Answer 293

- Non-itchy spotted rash on trunk and appendages - Patients experience fever, chills, headache, muscle pain, nausea, and vomitting - Organ failure can occur in severe cases

Question 294

Describe the pathogen that causes spotted fever rickettsiosis.

Answer 294

- Caused by Rickettsia rickettsii - Gram-negative, obligate intracellular pathogens (don't use glucose; oxidize AA and Krebs cycle intermediate) - Does NOT secrete any toxins (infect endothelial cells and cause damage to blood vessels)

Question 295

Describe the pathogenesis of spotted fever rickettsiosis.

Answer 295

1. Infected introduces R. rickettsii by feeding on blood for at least 6 hours 2. R. rickettsii triggers endocytosis by cells lining blood vessels (endothelium); then it lyses the endosome's membrane (now in cytosol) 3. R. rickettsii divide every 8-12 hours in the cytosol; daughters escape from long cytoplasmic extensions and infect adjacent endothelial cells 4. Damage to the endothelial cells leads to leakage of blood into the tissues (results in low BP and insufficient nutrient/O2 delivery to organs)

Question 296

Describe the epidemiology of spotted fever rickettsiosis.

Answer 296

- Transmitted via bite of infected hard tick (Dermacentor) - Male ticks infect female ticks during mating; female ticks trasmit bacteria to eggs forming in their ovaries - Hard ticks can survive without feeding for several years, making tick elimination in the wild problematic

Question 297

Transmitted via bite of infected hard tick (Dermacentor).

Answer 297

Spotted fever rickettsiosis

Question 298

Describe the diagnosis, treatment, and prevention of spotted fever rickettsiosis.

Answer 298

- Diagnosis: serological test for bacterial antigens OR detection of bacterial nucleic acid in lesion specimens - Treatment: antimicrobials (doxycycline for adults; chloramphenicol for children & pregnant women) - Prevention: use of tick repellents and avoidance of tick-infested areas

Question 299

Describe the signs and symptoms of cutaneous anthrax.

Answer 299

- Localized itching - Develop into painless black lesions (eschar) within 7-10 days

Question 300

Associated with painless black lesions (eschars).

Answer 300

Cutaneous anthrax

Question 301

Describe the pathogens/virulence factors involved in cutaneous anthrax.

Answer 301

- Caused by Bacillus anthracis; Gram-positive endospore-forming bacilli - Virulence factors include capsule, anthrax toxins, and endospore

Question 302

Describe the pathogenesis and epidemiology of cutaneous anthrax.

Answer 302

- Direct contact of endospores with wounded skin, infected animals (zoonotic disease), or contaminated animal products - Animal handlers (e.g., farmers) are susceptible

Question 303

Describe the diagnosis, treatment, and prevention of cutaneous anthrax.

Answer 303

- Diagnosis: appearance (black lesions) is diagnostic - Treatment: antimicrobials (doxycycline or ciprofloxacin) - Prevention: livestock vaccination

Question 304

How does gas gangrene come to be?

Answer 304

- Interruption of blood supply to tissue by a wound causes ischemia and necrosis of tissues - Creates condition of growth for anaerobic spore-forming bacteria

Question 305

Describe the signs and symptoms of gas gangrene.

Answer 305

- Death of muscle and connective tissue - Blackening of infected muscle and skin - Presence of gas bubbles - Shock, kidney failure, and death can occur quickly

Question 306

Describe the pathogens (and their virulence factors) that cause gas gangrene.

Answer 306

- Caused by several Clostridium species (mostly C. perfringens) - Gram-negative endospore-forming bacilli - Bacteria endospores survive harsh conditions - Vegetative bacterial cells secrete 11 toxins that lyse RBCs/WBCs, increase vascular permeability, and kill cells

Question 307

Describe the pathogenesis and epidemiology of gas gangrene.

Answer 307

- Clostridium does not affect healthy tissue and is not invasive - Traumatic event (surgery, puncture wounds, gunshot wound, crushing trauma, etc.) must introduce endospores into dead tissue - Despite therapeutic care, morality rate exceeds 40%

Question 308

Describe diagnosis and prevention of gas gangrene.

Answer 308

- Diagnosis: appearance is usually diagnostic - Prevention: proper cleaning of wounds

Question 309

Describe treatment for gas gangrene.

Answer 309

- Rapid treatment is crucial; considered a medical emergency - Surgical removal of dead tissue - Administration of antitoxin and antimicrobials (intravenous penicillin and clindamycin) - Application of oxygen under pressure

Question 310

What are some types of Poxviruses?

Answer 310

- Smallpox - Cowpox - Monkeypox

Question 311

Various types of skin lesions are caused by what virus?

Answer 311

Herpesvirus

Question 312

Chickenpox and Shingles is caused by what virus?

Answer 312

Varicella-zoster virus (VZV)

Question 313

Warts are caused by what virus?

Answer 313

Papillomavirus

Question 314

German measles (Rubella) is caused by what virus?

Answer 314

Rubivirus

Question 315

Measles (Rubeola) is caused by what virus?

Answer 315

Morbillivirus

Question 316

What Poxviruses cause human diseases?

Answer 316

- Smallpox - Orf - Cowpox - Monkeypox (rare in humans)

Question 317

The first human disease to be eradicated by vaccination.

Answer 317

Smallpox

Question 318

Describe the series of stages Poxvirus diseases progress through (i.e. signs and symptoms).

Answer 318

1. Macule (flat macules on and just below the epidermis) 2. Papule (lesions become raised sores) 3. Vesicle (lesion fills with fluid) 4. Pustule (pus forms in the lesion) 5. Crust (a dry layer forms on the epidermis) 6. Scar

Question 319

Poxviruses are _____ (DNA/RNA) viruses.

Answer 319

DNA viruses

Question 320

Poxviruses produce various ___________ that interfere with the immune response.

Answer 320

Proteins

Question 321

What specific type of Poxvirus causes smallpox?

Answer 321

- Orthopoxvirus (variola virus) - Only infects human cells

Question 322

Describe the pathogenesis of Poxviruses.

Answer 322

- Smallpox occurs by inhalation of virus (virus spread from the respiratory tract throughout the body) - Other Poxviruses are spread by direct contact

Question 323

What are the 2 different smallpox strains?

Answer 323

1. Variola major 2. Variola minor (less lethal)

Question 324

Describe the epidemiology of Poxviruses.

Answer 324

- Smallpox has been eradicated; but variola virus stocks maintained in US and Russian labs for research - Monkeypox cases have increased over the past decade

Question 325

Describe the treatment and prevention of Poxviruses.

Answer 325

- Treatment requires immediate vaccination - Vaccination program discontinued in 1970s following disease eradication - Some military and health care personnel are vaccinated

Question 326

Describe the signs and symptoms of Herpes infections.

Answer 326

- Slow-spreading skin lesions (can be painful and itchy) - Infections can occur at various body sites (oral cavity, fingers, skin, etc.) - Recurrence of lesions is common

Question 327

Herpetic gingivostomatitis occurs in the ___________.

Answer 327

Oral cavity

Question 328

What type of Herpes occurs on an infected finger?

Answer 328

Whitlow

Question 329

Herpes that can occur anywhere on the skin.

Answer 329

Herpes gladiatorium

Question 330

Describe the pathogens/virulence factors involved in Herpes infection.

Answer 330

- Caused by human Herpeviruses 1 and 2 - Both virus species can cause lesions at multiple locations - Produce various proteins that act as virulence factors

Question 331

Compare/differentiate between Herpesvirus (HHV) 1 and 2.

Answer 331

- HHV-1 = 90% of cold sores/fever blisters (whitlow); HHV-2 = 85% of genital herpes cases, 10% of oral herpes cases, 70% of neonatal herpes cases - HHV-1 transmitted through close contact; HHV-2 through sexual intercourse - HHV-1 latent in trigeminal/brachial ganglia; HHV-2 latent in sacral ganglia - HHV-1 lesions on face, mouth (and rarely trunk); HHV-2 lesions on external genitalia (and less commonly: thighs, buttocks, anus)

Question 332

Describe the pathogenesis of Herpes infections.

Answer 332

- Viruses may remain inactive inside infected cells for years - Painful lesions caused by inflammation and cell death - Fusion of infected cells forms syncytia

Question 333

Fusion of infected cells forms ___________.

Answer 333

Syncytia (this is in relation to Herpes infection)

Question 334

Describe the epidemiology of Herpes infections.

Answer 334

- Spread between mucous membranes of mouth and genital - Herpes infections in adults are not life threatening - Neonatal infections can be fatal

Question 335

Describe the diagnosis, treatment, and prevention of Herpes infections.

Answer 335

- Diagnosis: made by presence of characteristic lesions; immunoassay reveals presence of viral antigens - Treatment: chemotherapeutic drugs control the disease, but do NOT cure it - Prevention: healthcare workers can wear gloves to limit exposure

Question 336

Describe the signs and symptoms of warts.

Answer 336

- Benign epithelial growths on the skin or mucous membranes - Can form on many body surfaces

Question 337

Describe the pathogens/virulence factors involved in warts.

Answer 337

- Various Papillomaviruses cause warts - Some strains trigger oncogenes in host chromosome

Question 338

Describe the pathogenesis of warts (Papillomavirus).

Answer 338

- Warts develop several months after infection - Most warts are harmless - Papillomaviruses may precipitate some cancers

Question 339

Describe the pathogenesis/epidemiology of warts (Papillomavirus).

Answer 339

1. Papillomavirus is transmitted via direct contact OR from contaminated fomites 2. Virus multiplies within cells 3. Virus invades adjacent cells 4. Rapid growth of virus-infected cells creates wart 5. Virus is shed when dead skin cells are sloughed off

Question 340

Describe the diagnosis, treatment, and prevention of warts.

Answer 340

- Diagnosis: by observation - Treatment/prevention: various techniques to remove warts (new warts can develop as a result of latent viruses), vaccine available to prevent genital warts

Question 341

Describe the signs and symptoms of chickenpox.

Answer 341

- Highly contagious infectious disease caused by Varicella-zoster virus (VZV) - Characterized by lesions on the back and trunk that spreads across body - VZV becomes latent within sensory nerves

Question 342

Describe the signs and symptoms of shingles.

Answer 342

- Occurs following reactivation of VZV (e.g., after infected with chickenpox) - Lesions are localized to skin along an infected nerve - Pain may last after lesions have healed

Question 343

Describe the pathogenesis of chickenpox/shingles.

Answer 343

1. Inhalation of Varicella-zoster virus (VZV) 2. Infected cells replicate and release virus into the blood (viremia) and lymph 3. VZVs infect liver, spleen, and lymph nodes throughout body 4. 2nd viremia spreads VZVs to skin, causing extensive rash 5. VZVs shed through respiratory droplets and fluid from skin lesions 6. Immune system eliminates VZVs from blood and most cells 7. Some VZVs become latent/dormant in nerve ganglia 8. Upon reactivation, VZVs travel inside nerve cells, down the nerve, to infect skin cells 9. Rash develops in the band of skin innervated by the infected nerve

Question 344

Describe the epidemiology of chickenpox/shingles.

Answer 344

- Chickenpox occurs mostly in children; VZV infected 90% of children prior to immunization - Disease is more severe in adults - Only 15-20% of people who have had chickenpox develop shingles; risk of shingles increases with age

Question 345

Describe the diagnosis, treatment, and prevention of chickenpox/shingles.

Answer 345

- Diagnosis: based on characteristic lesions - Treatment/prevention: treatment based of relief of symptoms; vaccines available

Question 346

Describe the signs and symptoms of Rubella (German measles).

Answer 346

- Children develop a mild rash - Adults may develop arthritis and encephalitis - Congenital infection can result in birth defects or death of fetus

Question 347

Describe the pathogenesis of Rubella.

Answer 347

- Caused by Rubivirus - Infection spreads from the respiratory tract throughout the body via the blood - The immune response to infected cells contributes to disease severity in adults

Question 348

Describe the epidemiology of Rubella.

Answer 348

- Spread by respiratory secretions - Infects only humans

Question 349

Describe the diagnosis, treatment, and prevention of Rubella.

Answer 349

- Diagnosis: by observation of rash and serological testing - NO treatment available - Prevention: vaccine is available (aimed at preventing Rubella infections in pregnant women)

Question 350

Describe the signs and symptoms of Measles (Rubeola).

Answer 350

- Characterized by Koplik's spots (oral lesions of measles) - Numerous red lesions appear on the head and body - Sub-acute sclerosing panencephalitis is rare but deadly complication that can develop years after initial infection

Question 351

Describe the pathogens/virulence factors involved in Measles.

Answer 351

- Caused by Morbillivirus - Adhesion and fusion proteins help virus avoid immune recognition

Question 352

Describe the pathogenesis of Measles.

Answer 352

- Immune response to infection causes most symptoms - Disease can be fatal in children

Question 353

Describe the epidemiology of Measles.

Answer 353

- Highly contagious and spread via respiratory droplets - Humans are the only host

Question 354

Describe the diagnosis, treatment, and prevention of Measles (Rubeola).

Answer 354

- Diagnosis: based on signs of measles and confirmed with serological testing - Treatment: involves administration of vitamin A, antibodies against virus, and ribavirin - Prevention: MMR vaccine protects against measles

Question 355

Describe Erythema infectiosum (type of viral rash).

Answer 355

- Also referred to as "fifth disease" - Caused by B19 virus - Respiratory disease that manifests as a rash - Adults may also develop anemia and joint pain

Question 356

Erythema infectiosum is caused by what virus?

Answer 356

B19 virus

Question 357

Also referred to as "fifth disease."

Answer 357

Erythema infectiosum

Question 358

Describe Roseola (type of viral rash).

Answer 358

- Endemic disease of children - Caused by human Herpesvirus 6 (HHV-6) - Characterized by rose-coloured rash

Question 359

Roseola is caused by what virus?

Answer 359

Herpesvirus 6 (HHV-6)

Question 360

Describe the different location classifications of Mycoses (fungal diseases).

Answer 360

- Superficial = occur on the outer surfaces - Cutaneous (dermatophytoses) = occur in the skin - Subcutaneous = occur in the hypodermis and muscles - Systemic = affect numerous systems

Question 361

Most common fungal infection affecting the hair, nails, and outer skin layers.

Answer 361

Superficial mycoses

Question 362

What fungi causes superficial mycoses of the skin?

Answer 362

Malassezia furfur (normal inhabitant of human skin)

Question 363

Describe signs/symptoms of superficial mycoses of the skin.

Answer 363

- Hypo- hyper-pigmented patches of scaly skin - Caused by Malassezia furfur (normal inhabitant of human skin)

Question 364

Describe the pathogenesis and epidemiology of superficial mycoses of the skin.

Answer 364

- Fungi is non-invasive and produce keratinase (dissolves keratin) - Fungi are often transmitted via shared hairbrush and combs - Disease occurs most often in adolescents

Question 365

Describe the diagnosis, and treatment of superficial mycoses of the skin.

Answer 365

- Diagnosis: infected skin is pale under UV light; definitive diagnosis requires microscopic examination - Treatment: topical or oral drugs

Question 366

Describe characteristics of dermatophytoses (cutaneous mycoses).

Answer 366

- Cutaneous lesions caused by some fungi that grow in the skin - Caused by dermatophytes (Trichophyton, Microsporum, Epidermophyton floccosum) - Cell-mediated immune responses damage deeper tissues - Include Ringworm and Athlete's foot

Question 367

What 3 fungi genera cause dermatophytoses (e.g., Ringworm, Athlete's foot)?

Answer 367

1. Trichophyton 2. Microsporum 3. Epidermophyton floccosum

Question 368

Describe the pathogenesis of dermatophytoses.

Answer 368

- Fungi colonize skin, nails, and hair (use keratin as nutrient source) - Infection is rare (fungi must invade living layers of skin)

Question 369

Describe the epidemiology of dermatophytes.

Answer 369

- Dermatophytes are among the few contagious fungi - Classified by natural habitat (anthropophilic, zoophilic, geophilic dermatophytes)

Question 370

Describe the diagnosis and treatment of dermatophytoses.

Answer 370

- Diagnosis: by clinical observation; KOH preparation of skin/nail samples confirms diagnosis - Treatment: limited infections treated with topical agents; widespread ones treated with oral drugs

Question 371

Describe wound mycoses.

Answer 371

- Some fungi grow in deep tissues but do NOT become systemic - Fungi eventually grow into the epidermis to produce skin lesions

Question 372

What are the types of wound mycoses?

Answer 372

- Chromoblastomyocosis - Phaehyphomycosis - Mycetomas - Sporotrichosis

Question 373

Caused by 4 species of ascomycete fungi.

Answer 373

Chromoblastomycosis

Question 374

Describe chromoblastomycosis (type of wound mycoses).

Answer 374

- Caused by 4 species of ascomycete fungi - People who work barefoot in soil are at risk - Signs/symptoms: painless lesions that progressively worsen - Diagnosis: presence of golden brown bodies in skin sample - Treatment: requires removal of infected tissues and administration of anti-fungal drugs

Question 375

Describe phaehyphomycosis (type of wound mycoses).

Answer 375

- Caused by over 30 genera of fungi - Acquired when spores enter wounds - Disease is variable in presentation (depends on site of fungal colonization); permanently destructive to tissues - Diagnosis: observation of hyphae in skin sample, biopsy material, or cerebrospinal fluid - Treatment: anti-fungal agents like Itraconazole (ITZ inhibits synthesis of ergosterol)

Question 376

Describe mycetomas (type of wound mycoses).

Answer 376

- Caused by several genera of soil fungi (people who work barefoot in soil most at risk; pricks and scrapes introduce fungi) - Signs/symptoms: tumour-like lesions form on skin, fascia, and bones - Epidemiology: infections are prevalent in countries near the equator - Diagnosis: based on symptoms and presence of fungi in clinical samples - Treatment: involves surgical removal of mycetoma and anti-fungal therapy

Question 377

Caused by Sporothrix schenckii (resides in the soil).

Answer 377

Sporotrichosis

Question 378

Describe sporotrichosis (type of wound mycoses).

Answer 378

- Caused by soil fungi Sporothrix schenckii (occurs most often in gardeners/farmers; pricks and splinters introduce fungi) - Subcutaneous infection usually limited to arms/legs - Fixed sporotrichosis remains localized - Lymphocutaneous sporotrichosis occurs when the fungus enters the lymphatic system

Question 379

Describe the diagnosis, treatment, and prevention of wound mycoses.

Answer 379

- Diagnosis: based on patient's history, clinical signs, and observation of fungi in clinical samples - Treatment: cutaneous lesions are treated with anti-fungal drugs - Prevention: requires wearing proper attire to avoid inoculation of the fungus

Question 380

What 2 diseases are parasitic infestations of the skin?

Answer 380

1. Leishmaniasis 2. Scabies

Question 381

What pathogen causes Leishmaniasis?

Answer 381

Leishmania (protozoan transmitted via female sand flies)

Question 382

Protozoan transmitted via female sand flies.

Answer 382

Leishmania

Question 383

Describe the signs and symptoms of the types of Leishmaniasis.

Answer 383

- Cutaneous = large, painless skin lesions - Mucocutaneous = skin lesions enlarge to encompass mucous membranes - Visceral = spread by infected macrophages throughout the body

Question 384

Describe the pathogenesis and epidemiology of Leishmaniasis.

Answer 384

- Infected macrophages stimulate inflammatory responses - Leishmaniasis is endemic in parts of the tropic and subtropics

Question 385

Describe the diagnosis, treatment, and prevention of Leishmaniasis.

Answer 385

- Diagnosis: by microscopic identification of the protozoa - Treatment: most cases heal without treatment, but antimicrobials are needed for severe infections - Prevention: reducing exposure to the reservoir host

Question 386

Describe the signs and symptoms of Scabies.

Answer 386

- Characterized by intense itching and rash at infection site - Lesions common between the fingers; around the genitalia; and on the wrists, elbows, knees

Question 387

Describe the pathogenesis and epidemiology of Scabies.

Answer 387

- Caused by Sarcoptes scabiei (mite); inflammation and damage to nerve endings occur as the mites burrow - Itching blisters occur where female mites lay eggs - Mites transmitted via prolonged body contact

Question 388

Describe the diagnosis and treatment of Scabies.

Answer 388

- Diagnosis: made by observing mites, eggs, or fecal matter in the skin samples (or the characteristic burrows) - Treatment: mite-killing lotions

Question 389

Respiratory system ________________ between the atmosphere and the blood.

Answer 389

Exchanges gases

Question 390

Describe the 2 main parts of the respiratory system.

Answer 390

- Upper respiratory system (nasal cavity, pharynx): colonized by many microorganisms; normal microbiome limits growth of pathogens; normal microbiome may become opportunistic pathogens - Lower respiratory system (larynx, trachea, bronchi, diaphragm): microorganisms are NOT typically present

Question 391

What are the respiratory system barriers to infection?

Answer 391

- Tonsils (groups of lymphoid tissue); immune cells; chemical defences - Mucus contains various antimicrobial chemicals - Phagocytic alveolar macrophages - Normal microbiota

Question 392

What type of viruses cause the common cold?

Answer 392

Enteroviruses (Rhinoviruses)

Question 393

What bacteria causes Diphtheria?

Answer 393

Corynebacterium diphtheriae

Question 394

What are some infectious diseases of the upper respiratory tract, sinuses, and ears?

Answer 394

- Streptococcal respiratory diseases - Diphtheria - Rhinosinusitis - Otitis media - Common cold

Question 395

Describe the signs and symptoms of the various Streptococcal respiratory diseases.

Answer 395

- Pharyngitis: sore throat and difficulty swallowing (pus pockets on tonsils); often accompanied by fever, malaise, headache - Laryngitis/bronchitis can occur if infection spreads to lower respiratory tract - Complications in some cases include scarlet fever (skin rush); rheumatic fever (inflammatory disease of the heart, joints, skin, and brain); acute glomerulonephritis (kidney inflammation)

Question 396

Describe the pathogens/virulence factors involved in Streptococcal respiratory diseases.

Answer 396

- Caused by group A streptococci (Streptococcus pyogenes) - Variety of virulence factors: M protein, hyaluronic acid capsule, streptokinase, C5a peptidase, streptolysin O

Question 397

Describe the pathogenesis of Streptococcal respiratory diseases.

Answer 397

- Disease depends on the virulence factors present - Occurs when normal microbiota are depleted, large inoculum is introduced, or adaptive immunity is impaired

Question 398

Describe the epidemiology of Streptococcal respiratory diseases.

Answer 398

- Spread via respiratory droplets - Occurs most often in winter and spring

Question 399

Describe the diagnosis and treatment of Streptococcal respiratory diseases.

Answer 399

- Diagnosis: often confused with viral pharyngitis - Treatment: oral penicillin

Question 400

Describe the signs and symptoms of Diphtheria.

Answer 400

- Sore throat, localized pain, and fever - Presence of a pseudomembrane that can obstruct airways

Question 401

Describe the pathogens/virulence factors involved in Diphtheria.

Answer 401

- Caused by Corynebacterium diphtheriae (ubiquitous in animals and humans) - Diphtheria toxin: inhibits mRNA transcription and protein synthesis, causing cell death

Question 402

Describe how the diphtheria toxin works.

Answer 402

1. B subunit of diphtheria toxin attaches to human growth factor receptor 2. This triggers endocytosis 3. Subunit A is released from endocytic vesicle 4. Subunit A destroys elongation factor, preventing mRNA transcription in the nucleus of the human cell

Question 403

Describe the pathogenesis and epidemiology of Diphtheria.

Answer 403

- Spread via respiratory droplets or skin contact - Symptomatic in immunocompromised or non-immune individuals - Leading cause of death among un-immunized children

Question 404

Leading cause of death among un-immunized children.

Answer 404

Diphtheria

Question 405

Describe the diagnosis, treatment, and prevention of Diphtheria.

Answer 405

- Diagnosis: based on presence of pseudomembrane and a positive Elek test (detects diphtheria toxin from patient samples) - Treatment: antitoxin (passive immunization) and antibiotics - Prevention: DTaP vaccine

Question 406

Describe the signs and symptoms of Rhinosinusitis & Otitis Media.

Answer 406

- Malaise, headache, and inflamed nasal passages - Otitis Media results in severe pain in the ears

Question 407

Describe the pathogens involved in Rhinosinusitis & Otitis Media.

Answer 407

- Caused by various respiratory microbiota - May be due to damage to upper respiratory system and auditory tube

Question 408

Describe the pathogenesis and epidemiology of Rhinosinusitis & Otitis Media.

Answer 408

- Microbes in the pharynx spread to the sinuses via the throat - Middle ear is infected via the auditory tubes - Rhinosinusitis is more common in adults; Otitis Media is more common in children

Question 409

Describe the diagnosis, treatment, and prevention of Rhinosinusitis & Otitis Media.

Answer 409

- Diagnosis: symptoms are often diagnostic - Treatment: antimicrobials; nasal flushing (can reduce duration of symptoms) - Prevention: NO known way to prevent Rhinosinusitis

Question 410

Describe the signs and symptoms of the common cold.

Answer 410

- Sneezing, runny nose, congestion, sore throat, malaise, and cough

Question 411

Describe the pathogens/virulence factors involved in the common cold.

Answer 411

- Enteroviruses (rhinoviruses) = most common cause; non-enveloped +ssRNA viruses - Numerous other viruses cause colds

Question 412

Describe the pathogenesis of the common cold.

Answer 412

- Lower temperature of the nasal cavity promotes infection of cells and replication of cold virus - Cold viruses replicate in and kill infected cells

Question 413

Describe the epidemiology of the common cold.

Answer 413

- Rhinoviruses are highly infective - Spread by coughing/sneezing, fomites, or person-to-person contact - Develop some immunity to serotypes over time

Question 414

Describe the diagnosis, treatment, and prevention of the common cold.

Answer 414

- Diagnosis: signs and symptoms are usually diagnostic - Treatment: Pleconaril (antiviral drug) can reduce duration of symptoms and prevents acute asthma exacerbations - Prevention: hand antisepsis

Question 415

What are some bacterial diseases of the lower respiratory system?

Answer 415

- Bacterial pneumonia - Legionnaire's disease - Tuberculosis - Whooping cough (pertussis) - Inhalation anthrax

Question 416

What are some viral diseases of the lower respiratory system?

Answer 416

- Influenza - Coronavirus respiratory syndrome - Respiratory syncytial virus (RSV) infections

Question 417

What are some mycoses (fungal diseases) of the lower respiratory system?

Answer 417

- Coccidioidomycosis - Blastomycosis - Histoplasmosis - Pneumocystis pneumonia

Question 418

What bacteria can cause pneumonia?

Answer 418

- Streptococcus pneumoniae - Mycoplasma pneumoniae - Klebsiella pneumoniae

Question 419

What bacteria causes Legionnaire's disease?

Answer 419

Legionella pneumophila

Question 420

What bacteria causes tuberculosis?

Answer 420

Mycobacterium tuberculosis

Question 421

What bacteria causes whooping cough (pertussis)?

Answer 421

Bordetella pertussis

Question 422

What bacteria causes inhalation anthrax?

Answer 422

Bacillus anthracis

Question 423

The most serious and most frequent disease in adults.

Answer 423

Bacterial pneumonias

Question 424

Describe bacterial pneumonias.

Answer 424

- Lung inflammation accompanied by fluid-filled alveoli and bronchioles - Empyema (presence of pus) - Described by affected regions or organism causing the disease (lobar/pneumococcal, atypical/mycoplasmal, healthcare-associated)

Question 425

The presence of pus.

Answer 425

Empyema

Question 426

What are the types of pneumonia?

Answer 426

- Lobar or pneumococcal pneumonia - Atypical or mycoplasmal pneumonia - Healthcare-associated pneumonia

Question 427

Describe the signs and symptoms of lobar/pneumococcal pneumonia.

Answer 427

- Fever, chills, congestion cough, and chest pain; resulting in short, rapid breathing - Blood enters the lungs, causing rust-coloured sputum

Question 428

Describe the pathogens/virulence factors involved in lobar/pneumococcal pneumonia.

Answer 428

- Caused by Streptococcus pneumoniae (Gram-positive diplococci) - Virulence factors: adhesins, capsule, pneumolysin, secretory IgA protease

Question 429

Describe the pathogenesis and epidemiology of lobar/pneumococcal pneumonia.

Answer 429

- Inhalation of bacteria causes infection; bacterial replication causes damage to the lungs - Pneumococcal secretory IgA protease destroys host secretory IgA (on surface of mucosal membranes) - Accounts for most cases of bacterial pneumonia

Question 430

Accounts for most cases of bacterial pneumonia.

Answer 430

Lobar/pneumococcal pneumonia (Streptococcus pneumoniae)

Question 431

Describe the diagnosis, treatment, and prevention of lobar/pneumococcal pneumonia.

Answer 431

- Diagnosis: identifying diplococci in sputum smears - Treatment: penicillin (some strains are now resistant) - Prevention: vaccination

Question 432

Describe the signs and symptoms of primary atypical (mycoplasma) pneumonia.

Answer 432

- Fever, malaise, sore throat, and excessive sweating - Symptoms may last for weeks

Question 433

Describe the pathogens/virulence factors involved in primary atypical pneumonia.

Answer 433

- Caused by Mycoplasma pneumoniae - Virulence factors include an adhesion protein

Question 434

Describe the pathogenesis of primary atypical pneumonia.

Answer 434

- Bacteria colonize and kill epithelial cells - Mucus buildup and colonization by other bacteria

Question 435

Describe the epidemiology of primary atypical pneumonia.

Answer 435

- Bacteria spread by nasal secretions - Most common pneumonia in teenagers and young adults

Question 436

Most common pneumonia in teenagers and young adults.

Answer 436

Primary atypical (mycoplasma) pneumonia

Question 437

Describe the diagnosis, treatment, and prevention of primary atypical pneumonia.

Answer 437

- Diagnosis: difficult to diagnose - Treatment: erythromycin or doxycyline - Prevention: difficult since infected individuals may be asymtomatic

Question 438

Healthcare-associated pneumonia.

Answer 438

Klebsiella pneumonia

Question 439

Describe the signs and symptoms of Klebsiella pneumonia.

Answer 439

- Bloody sputum - Chills

Question 440

Describe the pathogens/virulence factors involved in Klebsiella pneumonia.

Answer 440

- Caused by Klebsiella pneumoniae - Virulence factors include a capsule - Immunocompromised patients at greater risk for infection (healthcare-associated pneumonia)

Question 441

Describe the diagnosis, treatment, and prevention of Klebsiella pneumonia.

Answer 441

- Diagnosis: identifying Klebsiella in sputum samples - Treatment: antimicrobials - Prevention: good aseptic technique by healthcare workers

Question 442

Can cause disease similar to pneumococcal pneumonia.

Answer 442

- Haemophilus influenzae - Staphylococcus aureus

Question 443

Causes pneumonic plague.

Answer 443

Yersinia pestis

Question 444

Causes psittacosis.

Answer 444

Chlamoydophila psittaci

Question 445

What diseases does Chlamoydophila pneumoniae cause?

Answer 445

- Pneumonia - Bronchitis - Rhinosinusitis

Question 446

Describe Legionnaire's disease.

Answer 446

- Typical pneumonia symptoms; pulmonary function can rapidly decrease - Most cases caused by Legionella pneumophila

Question 447

Describe the pathogenesis of Legionnaire's disease.

Answer 447

- Legionella pneumophila lives in and kills human cells (intracellular pathogen) - Causes tissue damage and inflammation

Question 448

Describe the epidemiology of Legionnaire's disease.

Answer 448

- Legionella survives in domestic water sources - The elderly, smokers, and immunocompromised individuals are at increased risk

Question 449

Describe the diagnosis, treatment, and prevention of Legionnaire's disease.

Answer 449

- Diagnosis: fluorescent antibody staining or serology - Treatment: quinolones or macrolides - Prevention: controlled by reducing bacterial presence in water

Question 450

Causes blue-colour colonies when grown on buffered charcoal yeast extract agar.

Answer 450

Legionella pneumophila

Question 451

The leading disease killer in the world.

Answer 451

Tuberculosis (but incidence has declined in the industrialized world)

Question 452

Describe the signs and symptoms of tuberculosis.

Answer 452

- Not always apparent - Initially limited to minor cough and mild fever

Question 453

Describe the pathogen involved in tuberculosis.

Answer 453

- Mycobacterium tuberculosis - Presence of mycolic acid gives unique features: slow growth, protection from phagocytic lysis, intracellular growth (e.g., in macrophages), resistance to many antimicrobial drugs

Question 454

Describe the pathogenesis of tuberculosis.

Answer 454

- Spread via inhalation of respiratory droplets - 3 types of tuberculosis: primary, secondary, disseminated

Question 455

What are the 3 types of tuberculosis?

Answer 455

1. Primary 2. Secondary (re-activation) 3. Disseminated (spread to other parts of body)

Question 456

What are tubercles?

Answer 456

Tightly packed macrophages surrounding the site of infection (by Mycobacterium tuberculosis).

Question 457

Describe primary tuberculosis.

Answer 457

1. Mycobacterium infects respiratory tract (via inhalation of respiratory droplets from infected individuals) 2. Alveolar macrophages phagocytize mycobacteria (but bacterium inhibits fusion of lysosomes to endocytic vesicles) 3. Bacteria replicate freely within macrophages, gradually killing them; get released and phagocytized by other macrophages 4. Infected macrophages present antigen to T cells, which produce lymphokines that attract and activate more macrophages (form tubercles over 2/3 months: tightly packed macrophages surrounding site of infection) 5. Other cells deposit collagen fibers, which enclose the tubercles; infected cells in the center die (produces caseous necrosis) 6. A "stalemate" between the bacterium and the body's defenses develops

Question 458

Describe secondary tuberculosis.

Answer 458

- Results when M. tuberculosis breaks the "stalemate" = ruptures tubercle and re-establishes an active infection - Re-activation occurs in about 10% of patients (with weakened immune systems)

Question 459

Secondary tuberculosis occurs in about __% of patients.

Answer 459

10%

Question 460

Describe disseminated tuberculosis.

Answer 460

Results when macrophages carry the pathogen via blood and lymph nodes to other sites of the body.

Question 461

Describe the epidemiology of tuberculosis.

Answer 461

- 1/3rd of the world's population is infected - Most deaths occur in Asia and Africa

Question 462

Describe the diagnosis, treatment, and prevention of tuberculosis.

Answer 462

- Diagnosis: tuberculin skin test (doesn't tell if active or not, just presence); chest X-ray (identify tubercles in the lungs) - Treatment: requires combination of drugs (there are drug resistant strains of M. tuberculosis) - Prevention: BCG vaccine available where tuberculosis is common

Question 463

Describe the signs and symptoms of whooping cough (pertussis).

Answer 463

- Initially cold-like, then characteristic cough develops - Poor oxygen exchange may produce cyanosis (blue tint to skin)

Question 464

Describe the pathogens/virulence factors involved in whooping cough.

Answer 464

- Caused by Bordetella pertussis - Produces numerous virulence factors (e.g., adhesins and several toxins)

Question 465

Describe the pathogenesis of whooping cough.

Answer 465

- Pertussis progresses through 4 phases (incubation; catarrhal; paroxysmal; convalescent)

Question 466

Describe the 4 phases of whooping cough.

Answer 466

1. Incubation (no symptoms; ~1 week) 2. Catarrhal (rhinorrhea, sneezing, malaise fever; highest titer of bacteria; ~2 weeks) 3. Paroxysmal (repetitive cough with whoops, vomiting, exhaustion; immune system highly active) 4. Convalescent (diminishing cough, possibly 2ndary complications)

Question 467

Describe the epidemiology of whooping cough.

Answer 467

- Highly contagious; bacteria spread through airborne droplets (don't survive long outside the body) - Considered a re-emerging disease

Question 468

Describe the diagnosis, treatment, and prevention of whooping cough.

Answer 468

- Diagnosis: symptoms are usually diagnostic - Treatment: primarily supportive - Prevention: DTaP vaccine

Question 469

Describe the signs and symptoms of inhalation anthrax.

Answer 469

- Initially resembles a cold or flu - Progresses to severe coughing, lethargy, shock, and death

Question 470

Describe the pathogens/virulence factors involved in inhalation anthrax.

Answer 470

- Caused by Bacillus anthracis (Gram-positive endospore-forming bacilli) - Virulence factors include a capsule and anthrax toxin

Question 471

Describe the pathogenesis and epidemiology of inhalation anthrax.

Answer 471

- Anthrax NOT spread from person-to-person - Acquired by contact or inhalation of endospores

Question 472

Describe the diagnosis, treatment, and prevention of inhalation anthrax.

Answer 472

- Diagnosis: based on identification of bacteria in sputum - Treatment: early and aggressive antimicrobial treatment is necessary - Prevention: anthrax vaccine is available to selected individuals

Question 473

Describe the signs and symptoms of influenza.

Answer 473

- Pharyngitis, congestion, cough, and myalgia (muscle ache) - Sudden fever distinguishes flu from a common cold

Question 474

Describe the pathogens/virulence factors involved in influenza.

Answer 474

- Caused by type A/B influenza virus; enveloped with segmented -ssRNA genome - Mutations in hemagglutinin and neuraminidase produce new strains; occurs via antigenic drift and shift - Concerns about appearance of new highly virulent strains

Question 475

Mutations in genes coding for what proteins lead to new strains of influenza?

Answer 475

- Hemagglutinin - Neuraminidase

Question 476

Describe antigenic drift.

Answer 476

1. Influenzavirus enters host cell 2. Mutations in antigen genes occur during viral replication 3. New strain of influenzavirus (differing slightly from original virus) exits the cell

Question 477

Describe antigenic shift.

Answer 477

1. 2 different strains of influenza A viruses enter the same host cell 2. Genes and antigens from both viral types are incorporated (combined) into new virions 3. A new influenzavirus (can be very different from the original 2 viruses) exits the cell

Question 478

Antigenic shift by influenza A virus occurs about __________________.

Answer 478

Once a decade

Question 479

Influenza ___ virus does NOT undergo antigenic shift.

Answer 479

Influenza B

Question 480

Describe the pathogenesis of influenza.

Answer 480

- Virus causes damage to the lung epithelium - Flu patients are susceptible to 2ndary bacterial infections

Question 481

Describe the epidemiology of influenza.

Answer 481

- Infection provides some immunological protection from similar strains - Concern that changes in type A influenza viruses may cause another major pandemic

Question 482

Describe the diagnosis, treatment, and prevention of influenza.

Answer 482

- Diagnosis: signs/symptoms during a community-wide outbreak are often diagnostic - Treatment: supportive care to relieve symptoms; antiviral drugs (oseltamivir & zanamivir) can be administered early in infection - Prevention: multivalent vaccine

Question 483

What are some types of coronavirus respiratory syndromes?

Answer 483

- Severe acute respiratory syndrome (SARS) - Middle East respiratory syndrome (MERS) - Coronavirus disease 2019 (COVID-19)

Question 484

Describe the signs and symptoms of coronavirus respiratory syndromes.

Answer 484

- High fever, shortness of breath, and difficulty breathing - Later, patients develop dry cough and pneumonia

Question 485

Describe the pathogens involved in coronavirus respiratory syndromes.

Answer 485

- Coronaviruses; SARS- and MERS-associated, and SARS-CoV2 (enveloped +ssRNA viruses) - Most diseases are usually mild - SARS and MERS have higher fatalities

Question 486

Describe the pathogenesis and epidemiology of coronaviruses.

Answer 486

- Coronaviruses spread via respiratory droplets - Virus spreads from the lungs to the heart/kidneys

Question 487

Describe the diagnosis of coronaviruses.

Answer 487

- Based on signs/symptoms - Confirmed by detection of viral nucleic acids, isolating the virus, or detection of antibodies against the virus

Question 488

Describe the treatment/prevention of coronaviruses.

Answer 488

- Treatment is supportive - Vaccine against MERS is available for young camels - Vaccines against COVID-19 available for humans

Question 489

Most common childhood respiratory disease.

Answer 489

Respiratory Syncytial Virus (RSV) infection

Question 490

Describe the the signs and symptoms of respiratory syncytial virus (RSV) infection.

Answer 490

- Leading cause of bronchiolitis, a major cause of pneumonia among children < 5 y/o - Fever, runny nose, cough in babies or immunocompromised individuals - Mild cold-like symptoms in older children and adults

Question 491

What type of viral genome does RSV have?

Answer 491

Enveloped -ssRNA

Question 492

Describe the pathogenesis of RSV infection.

Answer 492

- Virus causes syncytia (fusion of cells) to form in the lungs - Immune response to RSV further damages the lungs

Question 493

Describe the epidemiology of RSV infection.

Answer 493

- Transmission via close contact with infected persons - Less frequent = spread via respiratory droplets - Prevalent in the US - 98% of children in daycare centers are infected by age 3

Question 494

__% of children in daycare centers are infected with RSV by age 3.

Answer 494

98%

Question 495

Describe the diagnosis, treatment, and prevention of RSV infection.

Answer 495

- Diagnosis: made by immunoassay - Treatment: supportive treatment for young children - Prevention: includes aseptic technique of healthcare and daycare employees

Question 496

Describe the signs and symptoms of hantavirus pulmonary syndrome (HPS).

Answer 496

- Early symptoms include fever, fatigue, and muscle aches - Symptoms progress to cough, shock, and laboured breathing

Question 497

Describe the pathogen involved in HPS.

Answer 497

- Caused by Hantavirus; enveloped, segmented -ssRNA bunyavirus (has 3 genome molecules within capsid) - Transmitted from infected mice to humans via inhalation

Question 498

An enveloped/segmented -ssRNA bunyavirus.

Answer 498

Hantavirus

Question 499

Describe the pathogenesis of HPS.

Answer 499

- Hantavirus spreads throughout body via the blood - Infection causes widespread inflammation leading to shock - 50% of patients die from pneumonia and shock

Question 500

Describe the epidemiology of HPS.

Answer 500

- Transmitted to humans via contact with infected mice and their excrement/saliva - High rainfall and thick vegetation increases mice population = human disease more likely - High viral titers in the blood vessels of infected humans, but few viruses pass out of the lungs; person-to-person spread does NOT occur

Question 501

Describe the diagnosis and prevention of HPS.

Answer 501

- Diagnosis: based on characteristic symptoms - Prevention: requires control of rodents

Question 502

Describe the treatment of HPS.

Answer 502

- No pharmacological treatment is available - Treatment is supportive; pulmonary intubation, fever-reducing drugs, pain medication, and supplemental oxygen

Question 503

Cases of mycoses have increased over the last __ decades.

Answer 503

Last 2 decades

Question 504

AIDS patients are susceptible to _____ infections due to their compromised immune system.

Answer 504

Fungal infections

Question 505

Also known as valley fever.

Answer 505

Coccidioidomycosis

Question 506

Describe the signs and symptoms of coccidioidomycosis.

Answer 506

- Resembles pneumonia or tuberculosis; 60% of patients experience only mild respiratory symptoms - Can become systemic in immunocompromised persons

Question 507

Describe the pathogens/virulence factors involved in coccidioidomycosis.

Answer 507

- Caused by Coccidioides immitis and C. posadasii; dimorphic soil fungus (grows as a mycelium in soil and assumes yeast-form at human body temperature) - In the soil, produces chains of asexual spores (arthroconidia)

Question 508

Describe the pathogenesis of coccidioidomycosis.

Answer 508

- Arthroconidia from the soil enter the body through inhalation - Arthroconidia germinate in the alveoli into a form called a spherule (contain spores that can infect surrounding tissue)

Question 509

Describe the epidemiology of coccidioidomycosis.

Answer 509

- Almost exclusively in the southwestern US and northern Mexico - Disruption of the soil can disseminate arthroconidia

Question 510

Describe the diagnosis, treatment, and prevention of coccidioidomycosis.

Answer 510

- Diagnosis: presence of spherules in clinical specimens - Treatment: amphotericin B - Prevention: protective masks can prevent exposure to arthroconidia

Question 511

Describe the signs and symptoms of blastomycosis.

Answer 511

- Flu-like symptoms - Systemic infections can produce lesions on the face/upper body OR purulent lesions (contain pus) on various organs

Question 512

Describe the pathogen involved in blastomycosis.

Answer 512

- Caused by Blastomyces dermatitidis - Dimorphic fungus: grows as mycelium in soil (that is rich in organic material); assumes yeast-form at human body temperature

Question 513

Describe the pathogenesis of blastomycosis.

Answer 513

- Enters body through inhalation of fungal spores - In the lungs, spores germinate to form yeasts and multiply - Respiratory failure and death can occur in immunocompromised patients; relapse common in AIDS patients

Question 514

Describe the epidemiology of blastomycosis.

Answer 514

Endemic across the southeastern US and parts of Canada.

Question 515

Describe the diagnosis and treatment of blastomycosis.

Answer 515

- Diagnosis: based on identifying fungus in clinical samples - Treatment: amphotericin B

Question 516

Most common fungal disease affecting humans.

Answer 516

Histoplasmosis

Question 517

Describe the signs and symptoms of histoplasmosis.

Answer 517

- Asymptomatic in most cases - Symptomatic infection causes coughing with bloody sputum or skin lesions

Question 518

Describe the pathogens/virulence factors involved in histoplasmosis.

Answer 518

- Caused by Histoplasma capsulatum (intracellular parasite); dimorphic fungus found in moist soils (assumes a pathogenic yeast-form at human body temperature) - Histoplasma produces several proteins that inhibit macrophage activation and other host defences

Question 519

Describe the pathogenesis of histoplasmosis.

Answer 519

1. Humans inhale airborne spores from the soil 2. H. capsulatum first attacks alveolar macrophages in the lungs 3. Infected macrophages disperse the fungus via blood/lymph 4. Patients may develop chronic cutaneous histoplasmosis (ulcers), ocular histoplasmosis (inflamed red eyes), or systemic histoplasmosis (in immunocompromised patients: enlargement of spleen/liver; death may result)

Question 520

Describe the epidemiology of histoplasmosis.

Answer 520

- Prevalent in the eastern US - And parts of South America, Africa, and Asia

Question 521

Describe the diagnosis of histoplasmosis.

Answer 521

Diagnosis is based on identifying fungus in clinical samples.

Question 522

Describe the treatment of histoplasmosis.

Answer 522

- Infections in immunocompetent individuals typically resolve without treatment - Unresolved infections treated with amphotericin B and itraconazole - Maintenance therapy for AIDS patients is recommended

Question 523

Describe the signs and symptoms of pneumocystis pneumonia.

Answer 523

- Difficulty breathing - Anemia - Hypoxia - Fever

Question 524

Describe the pathogen involved in pneumocystis pneumonia.

Answer 524

- Caused by Pneumocystis jirovecii - Obligate parasitic fungus; normal member of the respiratory microbiome (but can become opportunistic)

Question 525

Describe the pathogenesis and epidemiology of pneumocytis pneumonia.

Answer 525

- Transmit by inhalation of droplets containing the fungus - In immunocompromised patients, it multiplies rapidly; extensively colonizing the lungs (cysts found in lung tissue) - Common disease in AIDS patients

Question 526

Describe the diagnosis and treatment of pneumocystis pneumonia.

Answer 526

- Diagnosis: based on clinical and microscopic findings - Treatment: trimethoprim and sulfamethoxazole (does not respond to anti-fungal drugs)