Host-microbiota: pathogenesis Flashcards
1
Q
what do pathogenic microorganisms have to do?
A
- establish entry, colonization and growth in the host
2
Q
What must be expressed to cause change in host function (disease)
A
- virulence
3
Q
What 2 factors allow entry of a pathogen?
A
- adhesion factors
- invasiveness
4
Q
What are the adhesion factors?
A
- tissue specificity (ex. ciliated cells - bordetella)
- host specificity (ex. neisseria gonorrhoea - urogenital tissue)
5
Q
What less specific cellular components aid in adhesion?
A
- capsule
- slime layer
- pili
- colonization factor antigens (CFA)
6
Q
What do pathogens have to attach to?
A
- mucosal material
7
Q
What factors contribute to invasiveness?
A
- penetrate epithelium
- may possess enzymes that aid in mucosal penetration
- need to establish certain point of occupancy
8
Q
What happens once a microorganism is able to multiply at an invasion site?
A
- colonization and growth occur
9
Q
What must microorganisms do to grow?
A
- sequester necessary nutrients and cofactors
10
Q
What is bacteremia?
A
- bacteria in bloodstream
11
Q
What must happen if bacteria is not host-adapted?
A
- must scavange
12
Q
What factors contribute to virulence?
A
- characteristics that aid in establishment and maintenance of disease (enzymes or toxins)
13
Q
WHat is hyaluronidase?
A
- breaks down hyaluronic acid (tissue cement) in host
14
Q
What are proteases? Give an example
A
- breakdown/depolymerize host proteins (ex. salmonella)
15
Q
What are nucleases?
A
- breakdown nucleotides
16
Q
What is actin filament depolymerization?
A
- penetration past mucosal barrier
17
Q
What are lipases?
A
- breakdown fats, can escape defences and enter other parts of body
18
Q
What is collagenase? Give an example
A
- breakdown collagen/connective tissue (ex. clostridium kills tissue)
19
Q
What are fibrinolytic enzymes?
A
- break through scabs (ex. streptokinase)
20
Q
What are the advantageous properties of fibrinolytic enzymes?
A
- clots/wall/isolate scabs and protect from potential invaders
21
Q
What are coagulases?
A
- cause clotting
22
Q
What are the advantageous properties of coagulase enzymes for bacteria?
A
- can wall bacteria off and protect them from immune cells - local infection
23
Q
What are the 2 types of toxins?
A
- endotoxins
- exotoxins
24
Q
What is an endotoxin?
A
- cell-bound and released in large amounts when cell lyses
- gram neg made of lipopolysaccharide material
25
Give an example of an endotoxin
- nisseria meningitidis
- grows abnormally, sheds endotoxic material
26
What is an exotoxin?
- protein released extracellularly as organism grows
- gram pos
- skips establishment in host, short incubation
27
Give an example of an exotoxin
- clostridia
28
what are the 3 general categories of endotoxins?
- cytolytic toxins
- A-B toxins
- superantigen toxins
29
What are cytolytic toxins? Give an example
- enzymatically attack cell constituents and cause disruption (attack enzymes needed to acquire nutrition)
- ex. phospholipids
30
What are A-B toxins?
- consist of 2 covalently bound subunits :B binds to host receptor, allows translocation of A (active portion) and elicits toxicity
31
What are superantigen toxins?
- stimulate large numbers of immune response cells which result in massive inflammatory reactions (kills own cells)
32
What is diphtheria toxin? what is it produced by?
- A-B toxin
- iron concentration in environment plays a role in production by corynebacterium diphtheriae
33
What is botulinum toxin?
- A-B toxin
- clostridium botulinum
34
When is botulinum produced?
- when organism is growing in preserved food product (not human host)
35
What is tetanus?
- A-B toxin
- C. tetani
36
What does tetanus result from?
- results from deeper penetration of C. tetani where conditions are more anoxic
37
What is death from tetanus a result of?
- severe neurological impairment
38
What is pseudomembranous?
- dense material of bacteria/defence cells that plug airway
39
What are enterotoxins?
- exotoxins that act on GI tract
- A-B toxin by vibrio cholerae
40
What is pseudomembranous?
- dense material of bacteria/defence cells that plug airway
41
What symptoms do enterotoxins cause?
- fluid in intestinal lumen = diarrhea
42
What happens when there is an osmotic imbalance?
- transmission of electrolytes and water is sent to gain balance on ion dump
43
What enteropathogenic bacteria produce toxins with similar modes of action to cholera toxin?
- salmonella and E. coli
44
What symptoms do endotoxins cause?
- fever from production of endogenous pyrogens by the host
45
What is pyrogen?
- activation of control centre of host
46
General endotoxin toxicity is ____ than exotoxins
- lower
47
What assay is highly sensitive for endotoxins?
- limulus test
48
What are virulence factors?
- structures/substances exported to bacterial cell surface or out of the cell
- anything that aids infection process/contributes to symptoms of disease
49
State and describe 5 factors/components associated with a bacterial cell that might support or contribute to its virulence
- They contain enterotoxins that act on the GI tract and cause massive secretion of fluid into the intestinal fluid
- Their flagellum allow for motility, H-antigen allows for adherence
- O antigens inhibit their demise in a phagocytic cell
- Their capsule is protective and antigen inhibits complement binding
- Their siderophores allow for iron uptake and nutrients
