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1
Q

what is a pathogen

A

an organism that causes disease

2
Q

what is pathogenicity

A

capacity to initiate disease

3
Q

what is virulence

A

capacity to cause disease and severity of the disease

4
Q

what is transmissibility

A

ability to transmit from human-to-human to reservoir-to-human

5
Q

what is survival infectivity

A

ability to breach host defences

6
Q

what are Koch’s postulates

A
  1. Microorganism must be found in diseased but not healthy individuals
  2. Microorganism must be cultured from the disease individual
  3. Inoculation of a healthy individual with cultured microorganism must cause the same disease
  4. Microorganism must be re-isolated from the inoculated, disease individual and matched to original microorganism.
7
Q

what are the steps to infection

A
transmission 
adherence 
invasion 
survival in host 
tissue damage
8
Q

what secretory systems have the capacity to transfer proteins directly from the cytoplasm

A

T1SS, T3SS, T6SS and T7SS

9
Q

what secretory systems can only secrete proteins from the periplasm to the outside environment

A

T2SS, T5SS T8SS T9SS

10
Q

what are the routes of entry for pathogens

A

respiratory, gastrointestinal, urinary tract, mucus membranes and skin

11
Q

what is adhesion

A

process by which organisms attach themselves to our cells

12
Q

how is initial attachment of bacteria to cells mediated?

A

fibrae/pilli and flagella

13
Q

what are EPS?

A

expolysacchardies they can further mediate attachment of pathogen to cells.

they are hydrophobic structures that displace water promoting closer contact between cells

14
Q

what is invasion

A

crossing host barriers, extra-cellular environments are harsh environments.

15
Q

what are the two things bacteria produce to induce entry into target cells

A

zipper and trigger

16
Q

what is zipper

A

expression of adhesion proteins that bind with high affinity to host receptors.

binding tricks the cell that another one is close by inducing membrane arrangements

bacteria is engulfed

17
Q

what is trigger

A

bacterial effector proteins are injected directly into the cytoplasm using T3SS.

activates signalling pathways = cytoskeleton rearrangements

18
Q

example of zipper

A

listeria

19
Q

example of trigger

A

salmonella and Shiga

20
Q

how do bacteria survive in the host?

A
  1. some escape into the cell cytoplasm rapidly multiplying and escaping to adjacent cells & repeating
  2. cytosol is a neutral pH, must have specific adaptations to import metabolic by-products from the cytoplasm
  3. bacteria need to hide from host immune responses such as autophagy.
  4. avoid lysosomal killing y interfering with endoscope maturation pathway
21
Q

what is the obligate survival?

A

pathogens require a host to fulfil their life cycle

22
Q

what is facultative survival?

A

pathogen can live in multiple different conditions

23
Q

what is extracellular survival

A

pathogens that thrive independent of a host cell

24
Q

example of what pathogens thrive independent of a host cell

A

E.Coli

25
Q

what are the two types of toxins

A

exotoxins and endotoxins

26
Q

what are exotoxins

A

toxins released into the environment can be gram negative and gram positive

27
Q

what are endotoxins

A

comprised of lipid A or LPS, only gram-negative.

28
Q

how do exotoxins stop self-attacking

A

they have A/b type subunits

o A+B synthesized and secreted separately
o A-B synthesized separately but associated during secretion
o A/B synthesized together but inactive until cleaved

29
Q

what is LPS and what does it degrade into

A

lipopolysaccharide is an endotoxin, degrades into non-immunogenic O-antigen and core part and lipid A.

30
Q

what is lipid A

A

Lipid A is highly pro-inflammatory binds to macrophages and monocytes that initiates a inflammatory response

31
Q

what is the function of endotoxins

A

responsible for stability and organisation of the cell wall