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MII > bacterial pathogensis > Flashcards

bacterial pathogensis Flashcards

1
Q

What are pathogens

A

Disease casing bacteria affecting all with normal host defences

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2
Q

What are non-pathogenic pathogens

A

Organisms that invade an individual without causing any obvious detectable symptoms

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3
Q

What are asymptomatic infections caused by

A

Microbes

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4
Q

Till when can organisms remain latent (dormant/inactive form)

A

Until they are reactivated with the recurrence of symptoms

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5
Q

What are the 3 consequences of antibiotic use in the alteration of normal gut flora

A

Sensitive gut flora killed => overgrowth with resistance => C. Difficile toxin production => diarrhoea and pseudomembranous colitis

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6
Q

What are the treatment options for affected normal gut flora from the use of antibiotics

A

-stop prescribing antibiotic
-oral metronidazole or vancomycin
-recovery requires reestablishment of normal flora

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7
Q

What is the first Koch’s postulates

A

1)the pathogen must be present in every case of the disease

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8
Q

What is the second Koch’s postulates

A

2)the pathogen must be isolated from the diseased host and grown in a pure culture

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9
Q

What is the third Koch’s postulates

A

3)the specific disease must be reproduced when a pure culture of the pathogen is inoculated into a healthy susceptible host

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10
Q

What is the fourth Koch’s postulates

A

4)the pathogen must be recoverable from the experimentally infected host

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11
Q

What are methods for the transmission of pathogens

A

Oral - oral
Feces - oral
Blood - blood
Sexual - contact

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12
Q

How is iron fundamental in infection

A

Without iron bacteria cannot power themselves to be pathogenic

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13
Q

What are 7 microbial pathogenicity factors

A

-toxins
-iron uptake
-adhesions
-LPS
-invasins
-slime
-enzymes

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14
Q

When does the first invasion occur for commensal microbes

A

When they breach the mucosal layer and eating + using nutrients from cells to produce factors and allow for pathogenicity

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15
Q

What are characteristics of flagellae

A

-multi-subunit structures
-mono or poly-trichous

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16
Q

How does flagellae help in reaching site of infection

A

Facilitates propulsion (propelling) to specific host targets

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17
Q

What is flagellae recognised by

A

By the innate immune system as PAMP recognised by TLR5

18
Q

What are characteristics of frimbriae

A

-hair like surface structures
-consist of various protein subunits

19
Q

What are the types of bacterial adhesion

A

-flagellae of gram-negative bacteria
-fimbriae and pili of gram-negative bacteria

20
Q

What do fimbriae interact with

A

Eukaryotic cells or inert surfaces via receptors at the tip

21
Q

What do many fimbriae receptors recognise

A

Sugars

22
Q

What are characteristics of pili

A

-structurally similar to fimbriae
-longer than fimbriae
-mostly only one present on surface

23
Q

What are pili involved in

A

In the conjugation (f-pili) or serve as receptors for phages

24
Q

Why is adhesion important for bacteria to host cells

A

-prevents bacteria from being washed off by fluid flow
-formation of a micro colony
-relevance to pathogenicity

25
Q

What do adhesins cause

A

Bacteria adhesion to host cell, formation of colonies and biofilms

26
Q

What do toxins do

A

Cause the destruction of tissue

27
Q

What do invasins do

A

Invasion and multiplication of bacteria

28
Q

What are the different type of toxins produced from bacteria

A

Exotoxins
Endotoxin
Enterotoxin

29
Q

What are exotoxins

A

Any toxin that is actively secreted by a bacterium in the environment or supernatant

30
Q

What is an endotoxin

A

A synonym for the LPS of gram-negative bacteria - only associated with gram -ive bacteria (cell-surface bound)

31
Q

What is an enterotoxin

A

An exotoxin that is effective in the gastrointestinal tract

32
Q

What is the mode of action of botulinum toxin (Botox toxin) (exotoxins)

A

-botulinum toxin acts at the end of motor end plate to prevent release of acetylcholine from vesicles
-results in lack of stimulus to muscle fibres
-irreversible relaxation of muscle and flaccid paralysis

33
Q

What is the mode of action of tetanus toxin (exotoxins)

A

-tetanus toxin binds to interneuron to prevent release of glycine from vesicles
-result in lack of inhibitory signals to motor neurons
-constant release of acetylcholine to muscle fibres
-irreversible contraction of muscles and spastic paralysis

34
Q

What are invasin factors

A

Protease
Glycosidases
Nucleases
Lipases

35
Q

How do the invasive factors lytic toxins damage membranes enzymatically and physically

A

Enzymatically - phospholipases
Physical - membrane-insertion

36
Q

How do invasins cause damage enzymatically

A

Produced as enzymes and degrade enzymatic pathways

37
Q

How do invasins cause damage physically

A

Invasins physically inserted into eukaryotic cell membranes to then bind to cholesterol or non-cholesterol structures

38
Q

What produces iron binding compounds

A

Siderophores

39
Q

What does a greater production of sidephores result in

A

The microbe being more virulent and pathogenic

40
Q

What are defensive pathogenic factors from the host defence mechanism

A

-polysaccharide capsule:negatively charged
-slime
-biofilm

41
Q

What are defensive pathogenic factors from the host immunogenic mechanism

A

-LPS:cytokines overstimulation -> leads to septic shock
-outer membrane proteins (OMPs): inactivate anti microbial peptides or complement factors

MII (21 decks)

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