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MBIO1010 > Part 7: Parthogenesis > Flashcards

Part 7: Parthogenesis Flashcards

(77 cards)

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1
Q

Infection

A

Growth of microbes that are not normally present in the host (regardless of whether or not the host is harmed)

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2
Q

Disease

A

Damage or injury that impairs regular host functions

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3
Q

Pathogen

A

A microbe that is able to cause disease

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4
Q

Opportunistic pathogen

A

A microbe that causes disease only in the absence of normal host resistance

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5
Q

Examples of opportunistic pathogens

A

Streptococcus pneumoniae and E. coli

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6
Q

Streptococcus pneumoniae

A

Causes pneumonia in immunocompromised patients

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7
Q

E. coli

A

Causes urinary tract infection when bacteria from feces are moved into the urethra

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8
Q

Pathogenicity

A

The ability to cause disease

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9
Q

Virulence

A

The severity of the disease that is caused - often given as an LD50 value

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10
Q

LD50

A

Number of cells of a pathogen (or dose of a toxin) that will cause death in 50% of infected animals

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11
Q

LD50 of Streptococcus pneumoniae

A

50 cells

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12
Q

LD50 of Samonella enterica

A

5000 cells

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13
Q

Pathogenesis

A

The process by which a disease develops

Steps that lead to an infection and tissue damage

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14
Q

Virulence factors

A

Genetically encoded traits that contribute to a pathogen’s ability to cause disease

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15
Q

Adherence

A

Ability for a pathogen to stick to a surface and begin colonization

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16
Q

Non-covalent adherence example

A

Capsules and slime layers

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17
Q

Streptococcus mutans non-covalent adherence factors

A

Uses slime layer to stick to teeth and form a biofilm

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18
Q

Streptococcus pneumoniae non-covalent adherence factors

A

Uses capsule to stick to cells in the lungs

Also protects the cell from phagocytes

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19
Q

Adhesins

A

Specific surface molecules that allow selective adherence to particular cell types

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20
Q

Enterotoxigenic E. coli adherence factors

A

Produce fimbriae and can adhere specifically to cells in the small intestine

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21
Q

Neisseria gonorrhoeae produces what adherence factors

A

Fimbriae that allow it to attach to mucosal epithelial cells - retract to bring bacteria close to the membrane

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22
Q

Opa proteins

A

Specifically attach to certain receptors on the host cell

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23
Q

Invasiveness

A

The ability of a pathogen to enter into host cells or spread through tissues

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24
Q

Virulence factors that promote invasiveness

A

Siderophores, exoenzymes, invasins

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25
Siderophores
Iron binding molecules
26
Siderophore mechanism
Host proteins transferrin and lactoferrin - sequester iron, making it unavailable for other microorganisms - limits the growth of invaiders Siderophores rip iron out of tissues to be used by bacteria
27
Types of exoenzymes
``` Hyaluronidase Collagenase Proteases, nucleases, and lipases Fibrinolysin Coagulase ```
28
Hyaluronidase
Hydrolyzes hyaluronic acid (cement that holds animal cells together) Allows pathogen to spread between cell
29
Collagenase
Degrades collagen | Allows pathogen to spread through tissues
30
Proteases, nucleases, and lipases
Degrade host macromolecules
31
Fibrnolysin
Dissolves fibrin clots
32
Example of fibrinolysin
Streptococcus pyogenes makes streptokinase
33
Coagulase
Induces fibrin clots
34
Example of coagulase
Staphylococcus aureus produces coagulase to protect it from phagocytes Keeps staph infections localized
35
Invasins
Proteins that allow bacteria to invade and enter directly into host cells
36
Listeria monocytogenes
Non-lactic acid, non-spore forming psychrotolerant member of Firmicutes
37
Where is Listeria monocytogenes found?
Unpasteurized dairy products, improperly packaged processed meats
38
Listeria monocytogenes produce
Invasins that promote phagocytosis by macrophages Hijacks the cytoskeleton to escape the phagolysosome Spreads from cell to cell Avoiding humoral immune response
39
Bacteremia
Bacteria in the blood | Can be carried to different organs and tissues
40
Septicemia
Bacteria multiplying in the blood (i.e., a blood borne systemic infection)
41
Septicemia can lead to
Sepsis - widespread systemic inflammation
42
Septic shock is caused by
Gram negative bacteria, gram positives: staphylococci and enterococci
43
Exotoxins
Proteins released by growing bacteria that inhibit host cell function (or kill host cells), usually heat labile, can be extremely toxic
44
Bacillus anthracis virulence factors
Capsules, exoenzymes, and the anthrax toxin
45
Anthrax toxin
Interferes with the immune response and kills macrophages
46
Categories of exotoxins
Cytoxins, AB toxins, superantigens
47
Cytoxins
Disrupt cytoplasmic membrane integrity - cell lysis and death
48
Examples of cytotoxins
Hemolysins, lecithinase or phospholipase, and leukocidins
49
Hemolysins
Lyse many cells (not just red blood cells)
50
What produces hemolysins?
Streptococcus pyogenes
51
Streptococcus pyogenes produces
Streptolysin
52
Streptolysin
Attacks sterols in the cell membrane
53
Lecithinase or phospholipase
Dissolves membrane lipids
54
Example of lecithinase or phospholipase
Clostridium perfringens - alpha toxin (gas gangrene)
55
Leukocidins
Destroy white blood cells
56
Example of leukocidins
Staphylococcus aureus - staphyloccal alpha toxin
57
Leukocidin mechanism
Toxin subunits insert into the membrane and oligomerize to form a heptamer
58
Heptamer
A membrane spanning pore | Cell contents leak out and the cell dies
59
AB toxin is made of
Active subunit and binding subunit
60
Example of AB toxin
Diphtheria toxin
61
What produces diphtheria toxin?
Corynebacterium diphtheriae
62
Diphtheria toxin mechanism
Subunit B - specifically binds to a protein on animal cells | Subunit A - then moves across the membrane (interferes with protein synthesis)
63
Where is the gene for the diphtheria toxin?
On a virus, not on the chromosome
64
Other AB toxin
Tetanus, botulism, and cholera toxins
65
Super antigens
Activate T-cells to elicit an extreme immune response Bind to MHC molecules TCRs outside the antigen binding site Bridge the gap and mimic proper antigen
66
What do superantigens activate?
Huge number of T cells
67
T cells produce
Cytokines
68
Cytokine reaction
Extreme immune response | Extreme fever, systemic inflammation, shock, death
69
Example of superantigen
Staphylococcus aureus' toxin shock syndrome toxin
70
Endotoxins
Lipopolysaccharide from the Gram negative outer membrane
71
Toxic part of endotoxin
Lipid A
72
Lipid A is released
When cells die
73
Which is more toxic: exotoxin or endotoxin
Exotoxins
74
Example of endotoxin
Samonellosis | Gram negative sepsis
75
Samonellosis mechanism
Colonizes the intestine - multiply to a huge number of bacteria As bacteria die, they release endotoxin
76
Symptoms of Samonella
Fever, diarrhea, generalized inflammation
77
Gram negative sepsis
Gram negative bacteria multiply in the blood Killed by immune system, releasing endotoxin Massive inflammation leads to septic shock and death

MBIO1010 (13 decks)

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