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bms662: microbial pathogen > C2 > Flashcards

C2 Flashcards

1
Q

How pathogen cause diseases

A
  • Portals of entry
  • Penetration of evasion of host defenses
  • Damage to host cells
  • Portals of exit
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2
Q

Example of portal of entry

A
  • Mucous membrane
  • Skin: hair follicles, sweat glands
  • Parenteral route:deeper tissue beneath skin
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3
Q

Most common portal of entry for pathogen in mucous membrane

A
  • Respiratory tract
  • GI tract
  • Genitourinary tract
  • Conjunctiva
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4
Q

Explain number of invading microbes

A
  • Likelihood of diseases depends on size of inoculum
  • Least no of pathogen to causes infection, more virulent
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5
Q

Define adherence

A

Capability of pathogenic microbes to attach to cells of body using adhesion factor

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6
Q

Explain specific adherence

A
  • Have adhesin or ligands that bind to host receptors
  • Complimentary to host receptors
  • Adhesion: glycoprotein, lipoprotein located in capsule, fimbriae, pili, flagella
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7
Q

Explain biofilm as adhesion factor

A
  • Produce glycocalyx that contributes to EPS
  • Allow biofilm attach to surface
  • Makes it harder for host to remove pathogen
  • Provide protection against immune & antibiotic
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8
Q

Define invasion of host cell

A

Spreading of pathogen throughout local tissues or body

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9
Q

Types of mechanism for host invasion

A
  • Capsule
  • Cell wall component
  • Enzymes
  • Antigenic Variations
  • Penetration into host cytoskeleton
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10
Q

Example of cell wall components for host invasion

A
  • M protein
  • Fimbriae & Opa
  • Mycolic acid
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11
Q

Types of enzymes for host invasion

A
  • Coagulase
  • Kinases
  • Hyaluronidase
  • IgA proteases: destroy host IgA antibody
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12
Q

Explain antigenic variation

A
  • Pathogen alter its surface antigen
  • To escape attack by antibody & immune cells
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13
Q

Explain penetration into host cytoskeleton

A
  • Use host actin to penetrate & move into cell actin
  • Use actin to penetrate intestinal epithelium
  • Produce invasin to rearrange actin to allow bacteria to enter into cell by causing cell membrane wrap around microbe
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14
Q

Mechanism of bacteria that use actin to spread to another host cells

A
  • Bacteria ingested through phagocytosis
  • Reside in phagosome
  • Lyse the phagosomal membrane
  • Escape into cytoplasm & divide
  • Induce actin polymerisation at one end
  • Form scaffolding- propel bact into cytoplasm
  • Released into cytoplasm
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15
Q

Types of infections

A
  • Local
  • Focal
  • Systemic
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16
Q

Explain local infection

A
  • Infection confined to small area of body
  • Near portal of entry
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17
Q

Explain focal infection

A

Localised pathogen or toxin spread to secondary infection

18
Q

Explain systemic infection

A

Infection become disseminated throughout the body

19
Q

Opsonin induce

A

Phagocyte to phagocytose (substance that opsonin bound)

20
Q

How pathogen cause damage to host cell

A
  • Use host nutrient
  • Direct damage
  • Production of toxin
21
Q

Explain of host nutrient

A
  • Iron essential for bacterial & human growth
  • Human produce transferrin, hemoglobin & lactoferrin
  • Iron chelators: bound to iron
22
Q

How pathogen use iron to damage tissue

A
  • Synthesis iron chelators called siderosphores
  • Able to compete with host iron chelators to bring iron into bacterium
23
Q

Explain direct damage

A
  • Growth & replication in host cell
  • Result in host cell lysis
  • Penetration through host cell causes damage
24
Q

Types of toxin

A
  • Exotoxins
  • Endotoxin
25
Q

Explain exotoxin

A
  • Produce inside bacteria as part of their growth
  • Toxin gene found on plasmid
  • Soluble in body fluids
26
Q

Function of exotoxin

A

Destroy certain host cell parts or inhibit particular metabolic function

27
Q

Types of exotoxin

A
  • Superantigens/ Type I toxin
  • Membrane disrupting toxin/ Type II toxin
  • A-B/ Type III toxin
28
Q

Explain superantigen/ Type I toxin

A
  • Bind to host surface but not translocated into cell
  • Cause proliferation of T cell
  • Induce cytokines
  • Excessive cytokines produce symptoms
29
Q

Explain membrane disrupting toxins/ Type II toxin

A
  • Disrupting eukaryotic cell membrane- lysis
  • Some are pore forming toxin
  • Some disrupt membrane by producing phospholipase & disrupting phospholipids portion of host cell membrane
30
Q

Example of pore forming toxin

A
  • Leukocidin: white blood cell
  • Hemolysin: red blood cell
31
Q

Explain Type III toxins

A
  • Exotoxins
  • Consist of 2 part (both are polypeptide)
  • A: active component - inhibit cell activity
  • B: bind surface receptors to bring A into host
  • Eg: botulinum, tetanus & cholera
32
Q

endotoxins consist of

A
  • Glycolipid
  • LPS macromolecule
  • 75% of outer membrane of Gram -ve bacteria
  • Cause lethal shock
33
Q

Glycolipid & LPS associated with what in endotoxin

A
  • Lipid A: Toxicity
  • Polysaccharide: Immunogenicity
34
Q

Mechanism to expel pathogen from respiratory tract

A
  • Coughing
  • Sneezing
35
Q

Mechanism that transport pathogens out of other portals of exit

A
  • Secretions
  • Excretions
36
Q

What is the example of vehicles for pathogen to leave body

A
  • Feces
  • Urine
  • Vaginal secretions
  • Sweats
37
Q

Blood borne diseases exit via

A

Insect/ Vector

38
Q

Respiratory infection utilize what organ as portals of exits

A
  • Mouth
  • Nose
39
Q

GI infection exit via

A

Feces or urine

40
Q

STD exit via

A
  • Urethra
  • Genital region

bms662: microbial pathogen (3 decks)

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