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MBIO1010 > Part 7: Parthogenesis > Flashcards

Part 7: Parthogenesis Flashcards

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
Q

Siderophores

A

Iron binding molecules

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26
Q

Siderophore mechanism

A

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

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27
Q

Types of exoenzymes

A 
Hyaluronidase
Collagenase
Proteases, nucleases, and lipases
Fibrinolysin
Coagulase
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28
Q

Hyaluronidase

A

Hydrolyzes hyaluronic acid (cement that holds animal cells together)
Allows pathogen to spread between cell

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29
Q

Collagenase

A

Degrades collagen

Allows pathogen to spread through tissues

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30
Q

Proteases, nucleases, and lipases

A

Degrade host macromolecules

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31
Q

Fibrnolysin

A

Dissolves fibrin clots

32
Q

Example of fibrinolysin

A

Streptococcus pyogenes makes streptokinase

33
Q

Coagulase

A

Induces fibrin clots

34
Q

Example of coagulase

A

Staphylococcus aureus produces coagulase to protect it from phagocytes
Keeps staph infections localized

35
Q

Invasins

A

Proteins that allow bacteria to invade and enter directly into host cells

36
Q

Listeria monocytogenes

A

Non-lactic acid, non-spore forming psychrotolerant member of Firmicutes

37
Q

Where is Listeria monocytogenes found?

A

Unpasteurized dairy products, improperly packaged processed meats

38
Q

Listeria monocytogenes produce

A

Invasins that promote phagocytosis by macrophages
Hijacks the cytoskeleton to escape the phagolysosome
Spreads from cell to cell
Avoiding humoral immune response

39
Q

Bacteremia

A

Bacteria in the blood

Can be carried to different organs and tissues

40
Q

Septicemia

A

Bacteria multiplying in the blood (i.e., a blood borne systemic infection)

41
Q

Septicemia can lead to

A

Sepsis - widespread systemic inflammation

42
Q

Septic shock is caused by

A

Gram negative bacteria, gram positives: staphylococci and enterococci

43
Q

Exotoxins

A

Proteins released by growing bacteria that inhibit host cell function (or kill host cells), usually heat labile, can be extremely toxic

44
Q

Bacillus anthracis virulence factors

A

Capsules, exoenzymes, and the anthrax toxin

45
Q

Anthrax toxin

A

Interferes with the immune response and kills macrophages

46
Q

Categories of exotoxins

A

Cytoxins, AB toxins, superantigens

47
Q

Cytoxins

A

Disrupt cytoplasmic membrane integrity - cell lysis and death

48
Q

Examples of cytotoxins

A

Hemolysins, lecithinase or phospholipase, and leukocidins

49
Q

Hemolysins

A

Lyse many cells (not just red blood cells)

50
Q

What produces hemolysins?

A

Streptococcus pyogenes

51
Q

Streptococcus pyogenes produces

A

Streptolysin

52
Q

Streptolysin

A

Attacks sterols in the cell membrane

53
Q

Lecithinase or phospholipase

A

Dissolves membrane lipids

54
Q

Example of lecithinase or phospholipase

A

Clostridium perfringens - alpha toxin (gas gangrene)

55
Q

Leukocidins

A

Destroy white blood cells

56
Q

Example of leukocidins

A

Staphylococcus aureus - staphyloccal alpha toxin

57
Q

Leukocidin mechanism

A

Toxin subunits insert into the membrane and oligomerize to form a heptamer

58
Q

Heptamer

A

A membrane spanning pore

Cell contents leak out and the cell dies

59
Q

AB toxin is made of

A

Active subunit and binding subunit

60
Q

Example of AB toxin

A

Diphtheria toxin

61
Q

What produces diphtheria toxin?

A

Corynebacterium diphtheriae

62
Q

Diphtheria toxin mechanism

A

Subunit B - specifically binds to a protein on animal cells

Subunit A - then moves across the membrane (interferes with protein synthesis)

63
Q

Where is the gene for the diphtheria toxin?

A

On a virus, not on the chromosome

64
Q

Other AB toxin

A

Tetanus, botulism, and cholera toxins

65
Q

Super antigens

A

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
Q

What do superantigens activate?

A

Huge number of T cells

67
Q

T cells produce

A

Cytokines

68
Q

Cytokine reaction

A

Extreme immune response

Extreme fever, systemic inflammation, shock, death

69
Q

Example of superantigen

A

Staphylococcus aureus’ toxin shock syndrome toxin

70
Q

Endotoxins

A

Lipopolysaccharide from the Gram negative outer membrane

71
Q

Toxic part of endotoxin

A

Lipid A

72
Q

Lipid A is released

A

When cells die

73
Q

Which is more toxic: exotoxin or endotoxin

A

Exotoxins

74
Q

Example of endotoxin

A

Samonellosis

Gram negative sepsis

75
Q

Samonellosis mechanism

A

Colonizes the intestine - multiply to a huge number of bacteria
As bacteria die, they release endotoxin

76
Q

Symptoms of Samonella

A

Fever, diarrhea, generalized inflammation

77
Q

Gram negative sepsis

A

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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