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Microbio Exam 2 > The parasite’s way of life; Damage by microbial toxins > Flashcards

The parasite’s way of life; Damage by microbial toxins Flashcards

1
Q

What are the six techniques that parasites use to live their way of life?

A
  1. Surface colonization
  2. Finding a nutritionally compatible niche
  3. Surviving host defenses
  4. Intracellular life
  5. Subverting host immune responses
  6. Transmission to a new host
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2
Q

Why do bacteria need to have the ability of surface colonization?

A
  • Preference of bacteria for particular locations in body
  • bacteria vary in specificity
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3
Q

What are the mechanisms on bacterium and host cells for surface colonization of bacteria?

A

Adhesins on bacterium
Receptors on host cell

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4
Q

What are examples of surface colonization for gram-negatvie bacteria?

A
  1. bacterial proteins on the tips of fimbriae and/or pili often interact with glycolipids and/or glycoproteins of host epithelial cells
  2. intimins (bacterial proteins at the the cell surface) interact with their own translocated intimin receptor (TIR) and cause actin polymerization
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5
Q

What do proteins on the tips of fimbriae of gram-negative bacteria interact with on host cells?

A

glycolipids and/or glycoproteins

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6
Q

What do the intimins on bacterial cells surface interact with?

A

their own translocated intimin receptor (TIR)

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7
Q

What are examples of surface colonization for gram-positive bacteria?

A
  • bind to host fibronectin which bins to integrins
  • serine rich repeat proteins (SRRPs) bind to sialic acid, keratin, or other NR domains
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8
Q

What do gram-positive bacteria use to bind to fibrinogen and collagen?

A

Microbial Surface Components Recognizing Adhesive Matrix Molecules or MSCRAMMS

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9
Q

many individuals in poor health are ___________-deficient

A

fibronectin
- balance shifts to more gram-negative bacteria since gram-positive bacteria use fibronectin to bind

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10
Q

Individuals in poor health have more gram __________ bacteria usually

A

negative

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11
Q

What bacteria and molecules are involved in oral infectious disease?

A
  • Streptococcus parasanguis: Fap1
  • S cristatus: SrpA
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12
Q

What bacteria and molecules are involved in endocarditis?

A
  • Streptococcus gordonii: Hsa and GspB
  • Staphylococcus aureus: SraP

these bind to platelets and form plaques

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13
Q

Why do bacteria have to find a nutritionally compatible niche?

A
  • intermittent availability of food for bacteria
  • adaptation to particular locations
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14
Q

What are the ways that bacterium can survive host defenses (innate)?

A
  • defending against complement (masking and inhibition)
  • subverting phagocytosis
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15
Q

How can microbes defend against complement?

A
  • use polysaccharide capsule to mask surface componenets
  • add sialic acid in surface to inhibit complement
  • C3b peptidasecleaves the complement component
  • long-chain “smooth” LPS limits accessof membrane attack complex (MHC)
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16
Q

What are the ways that microbes can subvert phagocytosis?

A
  • produce C5a peptidase
  • increase cAMP to inhibitory levels
  • kill phaogcytes (leukocidins)
  • escape ingstion (protein A)
  • survive inside phagocytes
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17
Q

What are the ways that pathogens can survive inside phagocytes?

A
  • inhibit lysosomal fusion with phagosome
  • escape into the cytoplasm (form pores in phagosome)
  • resist lysosomal enzymes
  • inhibit phagocyte’s oxidative pathway (respiratory burst)
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18
Q

How can pathogen penetrated nonphagocytic host cells?

A
  • internalins on bacteria interact with host E-cadherin
  • invasins on bacteria interact with host integrins
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19
Q

internalins on bacteria interact with host __________

A

E-cadherin

20
Q

invasins on bacteria interact with host ________

A

integrins

21
Q

How can pathogens transmit to other cells when inside a cell?

A

Actin-dependent intracellular motility and intercellular spread with possible tissue damage

22
Q

How do pathogens subvert the immune response?

A
  • immunosuppression
  • superantigens (diverting lymphocyte function)
  • changing antigenic coats
  • proteolysis of antibodies
23
Q

How can pathogens transmit to a new host?

A

-passive or active can be arbitrary
consider effects on host
- sneezing, coughing, diarrhea (active)
- insects

24
Q

What are the ways that microbes can cause lysis of host cells?

A
  1. growth of pathogen within host cells
  2. cell-mediated immunity (indirectly)
  3. Membrane-damaging toxins (apoptosis)
25
Q

Damage to the ___________ is proportional to number of bacteria inside cell

A

cell membrane

26
Q

What does inflammation cause in a healthy response?

A
  • increased blood supply (redness)
  • increased vascular permeability (edema)
  • chemotaxis (infiltration by phagocytes and lymphocytes)
27
Q

Why is there uncontrolled inflammation when a microbe infects occasionally?

A

exaggerated adaptive immune response = hypersensitivities

28
Q

What is a type I hypersensivity reaction?

A

allergy but can lead to anaphylaxis and shock

29
Q

What is a type II hypersensivity reaction?

A

bound antibodies leading to complement and leukocyte activation to surfaces

30
Q

What is a type III hypersensivity reaction?

A

bound antibodies leading to complement and leukocyte activation to soluble molecules, then immune complex deposition (e.g in glomeruli)

31
Q

What is a type IV hypersensivity reaction?

A

inflammation by purely CMI (cytokine-mediated inflammation) responses (not antibodies)

32
Q

What are the different ways in which toxins can act?

A
  • Modulation of targets inside a host cell
  • Acion on surface of a host cell
  • Action in the extracellular matrix
33
Q

What is a toxin?

A

Microbial product or component that can injure another cell or organism at low concentrations

34
Q

Many toxin-encoding genes are carried on plasmids or temperate bacteriophage genomes what does this mean?

A

easy to transfer to other, non-toxigenic bacteria

35
Q

What is an exotoxin?

A

secreted by pathogen

36
Q

What is a type III cytotoxin?

A

injected into host cells contact-dependent

37
Q

What are the common features of exotoxins?

A
  1. A-B toxins (2 components)
  2. Require activation (proteolysis or reduction of disulfides)
  3. Many are ADP-ribosyltransferases
38
Q

What do ADP-ribosyltransferases and Nicotinamide Adenine
Dinucleotides do to host proteins?

A

inactivates the target host protein

39
Q

On exotoxin what do the A and B domains do?

A

B domain is the binding domain (mediates the entry of the A domain into the host cell)
A is the enzymatic domain

40
Q

What are the ways that microbes can act on the surface of the host cell?

A
  • Membrane-damaging toxins= lipases, pore-forming toxins, hemolysins
  • Superantigens
  • Endotoxin = LPS of gram negative bacteria
41
Q

What is the active part of the LPS of gram-negative bacteria?

A

Lipid A

42
Q

What does a small amount of endotoxin cause?

A

normal immune response
- fever
- vasodilation
- increased antibody synthesis
- inflammation

43
Q

What does a large amount of endotoxin cause?

A

shock
intravascular coagulation

44
Q

What do exoenzymes do?

A

help microbes spread

45
Q

What are examples of exoenzymes?

A
  • collagenases, hyaluronidases, DNases
  • streptokinase
46
Q

How can you protect against exotoxins?

A

A. Immunization with toxoids
B. Treatment with antitoxins
“passive immunization”

Microbio Exam 2 (11 decks)

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