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Micro Lecture > Chapter 15 Microbial Mech Of Pathogenicity > Flashcards

Chapter 15 Microbial Mech Of Pathogenicity Flashcards

1
Q

What is Pathogenicity?

A

The Ability to cause disease

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2
Q

What is virulence?

What is Avirulent?

A

The extent of degree of Pathogenicity

Not pathogen

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3
Q

What are Koch’s Postulates?

A

Microorganisms are isolated form a diseased or dead animal

The microorganisms are grown in pure culture

The grown microorganisms are injected into a health animal

When the animal dies the identified microorganism should be present

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4
Q

What are the portals of entry?

A

Pathogens should gain access to the host to cause disease

Mucous membranes

Skin

Parenteral route

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5
Q

What is the most common route for infection and what do they include?

A

Mucous membranes

Respiratory tract
Gastrointestinal tract
Genitourinary tract
Conjunctiva -membrane covering the eyelid and eyeballs

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6
Q

What results from entry to the respiratory tract?

A

Common cold, Influenzam Pneumonia, measles

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7
Q

What is the outcome of bacteria ingested in the Gastrointestinal tract?

A

Usually they are destroyed by stomach pH. BUT

Some will survive and cause:
Hep A
Typhoid Fever
Amoebic dysentery 
Shigellosis
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8
Q

The diseases that ado survive the Gastrointestinal tract are transmitted how?

A

Excreted in feces which can be transmitted via oral fecal transmission

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9
Q

How are diseases transmitted via the Genitourinary tract?

Give examples

A

STD

HIV/AIDS
Genital Warts
Chlamydia
Gonorrhea
Syphilis
Herpes
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10
Q

How is the Skin a portal of entry?

A

Unbroken skin is a tough barrier to most microorganisms but they can enter through hair follicles and sweat glands

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11
Q

What is the Parenteral Route as a Portal of Entry?

A

A situation where microbes are introduced directly into the tissue beneath skin, or mucous membrane when these barriers are injured

Example: puncture, injections, bites, cuts, wounds

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12
Q

What is the preferred portal of entry?

A

Each specific microbe has a preferred portal of entry

Salmonella typhi = swallowed

Streptococcus is inhaled and causes pneumonia

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13
Q

How are the degrees of virulence and lethal dose of a microbe expressed as?

A

ID50: Infectious dose for 50% of the test population

LD50: Lethal dose (of a toxin) for 50% of the test population

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14
Q

What is the portal of entry and ID50 of Bacillus anthracis?

A

Skin = 10-50 endospores

Inhalation = 10,000 - 20,000 endospores

Ingestion = 250,000 - 1,000,000

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15
Q

Toxins

What is the portal of entry and ID50 for:

Botulinum
Shiga toxin
Staphylococcal enterotoxin

A

Botulinum = .03 ng/kg

Shiva toxin = 250 ng/kg

Staphylococcal enterotoxin = 1350 ng/kg

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16
Q

What is adherence? How and where does this take place on a pathogen

A

Attachment is a necessary step in infection

This attachment is between surface molecules on the pathogen and surface receptors on the host cells

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17
Q

What is the attachment called?

What else can communities form?

A

This attachment is called Adhesions or adherence

Some form biofilms: come together in masses, cling to surfaces and share nutrients

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18
Q

What are the surface molecules on the pathogen called?

A

Adhesins or ligands

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19
Q

Most adhesions are made of?

Where are these adhesions located?

A

Glycoproteins
Lipoproteins

Pili
Fimbriae
Flagella
Glycocalyx

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20
Q

What are the receptors on host cells typically made of?

A

Sugars like mannose

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21
Q

Can surface olecules on a pathogen bind to and surface of the host cell?

A

No, they bind specifically to complementary surface receptors of the host cell

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22
Q

What does Streptococcus mutans cause?

A

Causes tooth decay

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23
Q

What does Shigella cause?

A

Cause gastrointestinal diseases

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24
Q

What does Listeria monocytogenes cause?

A

Causes septicemia, CNS infections

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25
Q

What does Staphylococcus aureus cause?

A

Causes skin infections

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26
Q

What does Neisseria gonorrhoeae cause?

A

Gonorrhea

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27
Q

What are the three ways pathogens penetrate host defense?

A
  1. Capsules
  2. Components of cell wall
  3. Enzymes
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28
Q

What does capsules do for the pathogen when invading a host?

A

Prevent phagocytosis of

Streptococcus pneumonia
Haemophilus influenza
Klebsiella pneumonia

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29
Q

How does the cell wall contribute to a pathogens virulence?

A

Components of the cell wall contribute to virulence:

M protein resists phagocytosis
-Streptococcus pyogenes
Opa protein use to attach to the host (forms opaque colonies)
-Neisseria gonorrhoeae
Mycolic acid (waxy lipid) resists digestion
-Mycobaterium tuberculosis

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30
Q

How do enzymes help pathogens penetrate the host defense?

A

These are exoenzymes

They break open cells
They dissolve blood clots

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31
Q

What does the enzyme coagulase do?

A

Coagulates fibrinogen in the blood

-staph aureus (coag +)

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32
Q

What are Kinases?

Which microorganisms make kinases and what are they and what do they do?

A

Dissolve blood clots

Streptococcus pyogenes produces fibrinolysin (streptokinase)

S. Aureus produces staphylokinase

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33
Q

What hydrolyzes hyaluronic acid?

What does it do?

A

Hyaluronidase

Dissolves connective tissue: blackening of infected wound

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34
Q

What does Collagenase do?

What does this?

A

Hydrolyzes collagen

-Clostridium: facilitate spread in gas gangrene

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35
Q

What is the function of IgA proteases?

A

Destroys IgA antibodies

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36
Q

What are Necrotizing factors?

A

Causes necrosis

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37
Q

What does Lecithinase do?

A

Destroys RBC plasma membrane

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38
Q

What is the function of Hemolysin?

A

Causes lysis of erythrocytes (RBC)

  • Streptococcus: streptolysins
  • Staphylococcus
  • Clostridium perfingens: Gas gangrene
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39
Q

What are the different kinds of Streptolysins?

A

Streptolysin O (SLO)

Streptolysin S (SLS)

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40
Q

What is Antigenic Variation?

A

Some pathogens are capable of changing their surface Ag, thereby evading the body immune system

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41
Q

What does the body produce in response to pathogens?

How does this take place?

A

Body produces Antibodies (Ab) in response to Antigen (Ag)

Antibody destroys or inactivated the antigen

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42
Q

What are invasions?

A

They are proteins produced by microbes after attachment. They change the appearance of the plasma membrane meaning changes the actin filaments of the cytoskeleton

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43
Q

What disrupts the cytoskeleton of host cell by causing membrane ruffling?

A

Salmonella typhimurium

This allows the pathogen to sink into the ruffles of the host and eventually be taken in.

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44
Q

What is used by Shigella and Listeria to bridge the junction and to move form cell to cell?

A

Cadherin

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45
Q

What are the 4 different mechanisms that microorganisms can damage host cells by?

A

Using host’s nutrients: Siderophores
Direct Damage to host cells by invasion
Produce Toxins
Inducing hypersensitivity

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46
Q

What is obtained by bacteria by using Siderophores?

This is required for bacterial growth?

A

Iron

Iron is required for growth of bacteria

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47
Q

What does Siderophores do?

A

Binds unbound free iron in the host that is not bound to transferrin or hemoglobin

48
Q

What are ways to cause direct damage to the host cell after attachment?

A

Disrupt host cell function

Produce Waste products

Pathogens multiply in cell and the cell ruptures

49
Q

How are some organisms brought into the host cell that fools the host cell?

What are a few organisms that do this?

A

Some organisms induce the host cell to engulf them by a process resembling phagocytosis

Then after they cause damage and are released the infect other cells.

Ex. E.coli, Shigella, Salmonella, Neisseria gnorrhaeae

50
Q

What causes the most damage to host cells?

A

Toxins

51
Q

Exotoxins are divide into 3 types?

A

A-B-toxins

Membrane-disrupting toxins

Superantigens

52
Q

What is the action of a A-B Exotoxin?

A
  1. Bacterium produces and releases exotoxins
  2. B(binding) component of exotoxin attaches to host cell receptor
  3. A-B exotoxin enters hot cell by endocytosis
  4. A-B exotoxins enclosed in pinched-off portion of plasma membrane during pinocytosis
  5. A-B components of exotoxins separate. The A component alters cell function by inhibiting protein synthesis. The B component is released from the host cell
53
Q

Membrane disrupting toxins do what to the membrane of the host?

A

Lyse (kill) the host cells by:

  1. Making protein channels in the plasma membrane
  2. Disrupting phospholipid bilayer
    Ex. Clostridium perfringens
54
Q

Leukocidins, Hemolysins, Streptolusins all do what and to which cells?

A

Leukocidins: Kill phagocytic leukocytes

Hemolysins: kills RBC

Streptolysins: by streptococcus

All make protein channels that all for the contents of the host cell to come out causing lysis of the cell.

55
Q

What are Superantigens?

A

They cause very intense immune response due to the release of cytokines from host cells

Basically an over kill or too many WBC released to the site of infection.

56
Q

What are the symptoms of Superantigens?

A

Fever, nausea, vomiting, diarrhea, shock, and death

57
Q

What are some examples of Superantigens and what does it cause?

A

Staphylococcus

Causes food poisoning and TSS

58
Q

What is Toxigenicity?

What does it contribute to?

A

Toxingenicy: Ability to produce toxin

Toxins are substances that contributes to Pathogenicity

59
Q

What do Toxins cause?

A

Fever
Diarrhea
Affect the nervous system
Destroy RBC

60
Q

What is Toxemia?

A

Presence of toxin in the host’s blood

61
Q

What is Toxoid?

A

Inactivated toxin used in a vaccine

62
Q

What is Antitoxin?

A

Antibodies against a specific toxin

63
Q

What are exotoxins?

A

Are produced inside bacterial cell and release into the surroundings

64
Q

What are the characteristics of exotoxins?

A

Mostly made by G+

Their genes are carried on plasmids or phages

65
Q

What are the 3 groups of Exptoxins and what do they do?

A

Cytotoxins - kills host cells

Neurotoxins - affects nervous system

Enterotoxins - affects the gastrointestinal tract

66
Q

Diphtheria toxin is produced by what pathogen? What does this toxin cause?

A

Produced by Corynebacterium diphtheria

The toxin is produced by the gene (Tox) in a phage

It inhibits protein syntheses in host cell

67
Q

Diphtheria toxin is an example of what type of toxin?

A

A-B toxin

68
Q

What Erythrogenic toxin is deactivated by O2?

A

Streptolysin O (SLO)

69
Q

What Erythrogenic toxin has an affinity for albumin found in serum?

A

Streptolysin S (SLS)

70
Q

Toxins that damage blood capillaries and produce red skin rash is called?

A

Scarlet Fever

71
Q

Clostridium botulinum forms what toxin?

What type of toxin is this and what does it cause?

A

Botulinum toxin.

Neurotoxin that inhibits release of neurotransmitter ACh that prevents muscle contraction resulting in flaccid paralysis (diaphragm can’t contract and patient can’t inhale)

A-B neurotoxin

72
Q

What are the characteristics of Tetanus toxin?

A

Neurotoxin by C.tetani

Causes muscle contraction or Lockjaw

A-B neurotoxin

73
Q

What are Vibrio enterotoxin?

How are these toxins brought into the host?

What does it cause?

A

By V.cholerae

They are ingested

Causes sever diarrhea with vomiting because epithelial cells release large large amount of fluid and electrolytes

A-B enterotoxin called Cholera toxin

74
Q

What produces TSS?

A

S.aureus

It’s superantigen enterotoxin

75
Q

How does Endotoxins differ from exotoxins?

A

Located within bacterial cells and are part of the outer portion of the cell wall of Gram negative bacteria.

The lipid portion of the Lipopolysaccharides lipid A is the endotoxin.

76
Q

When are endotoxins released?

A

During Multiplication and when bacterial cells die lysis

77
Q

What do endotoxins cause?

A

Fever (pyrogens response)

Septic shock or endotoxic shock - which is a drop in blood pressure

Can also cause blood clotting and death

78
Q

What is a example of a pathogen that could cause blood to clott

A

Salmonella typhi, Proteus (urinary tract infections), Neisseria meningitis

79
Q

Phagocytosis of gram negative bacteria endures the release of TNF, what does TNF cause?

A

Damages blood capillaries which causes los of large amounts of fluid which leads to shock due to a drop in Blood pressure

80
Q

What is the Pyrogenic response?

A

Macrophages ingest G- bacteria
LPS released toxin
Release of cytokines IL-1 and TNF-alpha that travel to the hypothalamus
Releases prostaglandins that resets the norm temp higher this is fever

81
Q

What does Asprin do to fevers?

A

Reduces fever by inhibiting synthesis of Prostaglandins

82
Q

What do Macrophages release?

A

TNF or Cachectin from ingesting G- bacteria

Damages blood capillaries - fluid loss

Drops blood pressure which causes shock

83
Q

What does Salmonella cause?

What does Proteus cause?

Neisseria meningitis?

A

Typhoid fever

Urinary tract infection

Meningitis

84
Q

What are the characteristics of Exotoxins?

A

Mostly G+

Relation to microbe: BY-products of growing cell
Chemistry: Protein
Doesn't cause fever
It is neutralized by antitoxin
It's LD50 is small
85
Q

What is Lysogenic conversion?

A

DNA of a virus is incorporated in to the DNA of a host cell becoming a prophage that sits latent not causing lysis of a cell.

The host bacterial cell and its progeny can exhibit new characteristics encoded by the bacteriophages DNA this change is Lysogenic conversion.

86
Q

Lysogenic conversion enables what to take place?

A

Prophage will enable bacteria to produce toxins:

Diphtheria toxin

Botulinum neurotoxins

Capsule produced by Streptococcus pneumoniae

87
Q

What are the characteristics of Endotoxins?

A

Source: Gram negative

Relation to Microbe: Outer membrane

Chemistry: Lipid A

Fever? Yes
Not neutralized by antitoxin
Has a relatively large LD50

88
Q

What is The LAL Assay and what is it used for?

A

Limulus amoebocyte lysate assay is a test to detect endotoxins

89
Q

What are amoebocytes?

What do these cells do?

A

They are WBC’s of horseshoe crab

These cells contain proteins that clot blood

It’s endotoxin causes lysis of cells and release protein and clots blood

90
Q

The visible effects of a viral infraction are know as?

A

Cytophathic Effects (CPE) of viruses

91
Q

What are the characteristics of CPE’s?

A

Intercellular parasites

Need to attach to host cells

92
Q

How do CPE’s kill?

A

Multiplication and producing large number of particles

Change permeability of host cell membrane

Stop protein, DNA or RNA synthesis

93
Q

If CPE causes the death of the cell it is called?

A

Cytocidal effect

94
Q

What are some examples of CPE’s?

A

Herpes Simplex Virus stops Mitosis

Viruses causes lysosomes to release their enzyme and destroy Intracellular contents of the cell

95
Q

What are inclusion bodies and what are they used for?

A

Granules in the cells and they are used for the identification of:

Rabies virus

Measles Virus

Small Pox Virus

96
Q

What is a Syncytium?

A

Several adjacent infected cells fuse to form a very large multinucleated cell called a Syncytium

97
Q

What can CPE’s cause to the surface of infected cells?

A

They can induce antigenic changes of the surface of infected cells

98
Q

If CPE’s cause chromosomal changes what are these changes called?

A

Oncogenes (cancer causing genes)

99
Q

What is lost when Oncogenes transform cells into a tumor?

A

Cells loss their contact inhibition which causes the over production of cells and they now touch forming a tumor.

100
Q

Even though Fungi can cause disease what is unique about it virulence factors?

A

Do not have a well defined set of virulence factors

101
Q

What are the toxins that fungi produce?

A

The products of fungi is what is toxic to fungi, however the toxin is only an indirect cause of disease because fungus is already growing in or on the host.

102
Q

What of the fungus cause the disease?

A

Fungal waste products may cause symptoms

103
Q

What can happen with chronic fungal infections?

Give an example?

A

Chronic infections provoke an allergic response

Example: athletes foot.

104
Q

What is Trichothecene toxin?

What do they cause?

A

They are fungal toxins that inhibit protein synthesis in eukaryotic cells

Ingestion of these toxins cause headaches, chills, severe nausea, vomiting and visual disturbances

105
Q

What pathogens cause Trichothecene?

A

Fusarium and Stachybotrys

106
Q

Which fungi cause skin infections that secrete proteases?

A

Candida albicans and Trichophyton

107
Q

What do these enzymes of these proteases do to the host cell membranes?

What pathogen causes this and what does it produce?

A

They modify the host cell membranes to allow attachment of the fungi. Produces a capsule that helps it resist phagocytosis.

Cryptococcus neoformans (meningitis)

108
Q

What is the disease Ergot toxin? What does it cause?

A

Common during the Middle Ages

It’s an alkaloid that causes hallucination like LSD

It constricts capillaries and can cause gangrene of the limbs by preventing proper blood circulation in the body.

109
Q

What pathogen grows on grains that’s an Ergot toxin?

A

Claviceps purpurea

110
Q

What is the toxin that usually gets peanut butter recalled?

A

Aflatoxin, which has carcinogenic properties.

Aspergillus flavus (mold) : could be mutagenic once its ingested into the human body.

111
Q

What are Mycotoxins?

A

Some mushrooms produce these.

Examples are phalloidin and amanitin

112
Q

What mushrooms are referred to as the death cap mushroom?

What type of toxins are these?

A

Phalloidin, and amanitin

Amanita

Neurotoxins

113
Q

What of the Protozoa cause diseases?

Plasmodium reproduces how?

A

Protozoan waste products may cause symptoms

Some reproduce inside the cell and causes it to rupture

114
Q

How do Protozoa avoid the host defenses?

A

They grow with in phagocytes and they alter their Antigenic Variation

115
Q

What is antigenic Variation?

A

Microbes can make many different antigens or alter their surface proteins to evade the host immune system

116
Q

What are the Portals of Exit and method of exit?

A

Respiratory tract- coughing and sneezing

Gastrointestinal tract- feces and saliva

Genitourinary tract- urine and vaginal secretions

Skin
Blood- biting Arthropods and needles or syringes can transfer blood-Bourne pathogens

Micro Lecture (11 decks)

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