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Biology + Microbiology > Pathogenicity & Virulence > Flashcards

Pathogenicity & Virulence Flashcards

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1
Q

What is a pathogen?

A

A bacterium, virus or other microorganism that can cause disease

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2
Q

What is a primary pathogen?

A

Can cause disease in a host regardless of the host’s resident microbiota or immune system

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3
Q

What is an opportunistic pathogen?

A

Can only cause disease in situations that compromise the host defences

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4
Q

Give an example of host difences?

A

Body barriers , immune system or normal microbiota

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5
Q

What is pathogenicity?

A

The ability of an organism to cause disease
An organism is either pathogenic or isn’t

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6
Q

What is virulence?

A

The degree of intensity of damage caused by the organism
A measurement of pathogenicity

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7
Q

What is avirulent?

A

Not harmful
Mild infection no severe
Fever, headaches

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8
Q

What is highly virulent?

A

Almost always lead to disease state
Multi-organ and body system failure

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9
Q

What affects virulence?

A

How well it adheres to host cells
Its ability to colonise the host
Its ability to invade host tissues
The arsnal of virulence factors

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10
Q

Are highly virulent pathogens gram positive?

A

Yes

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11
Q

What are the symptoms of the highly virulent Bacillus anthracis?

A

High fever, difficulty breathing, vomiting, couching up blood, severe chest pains

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12
Q

How can virulence be measured?

A

Through tests on animals

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13
Q

What is median infection dose (IDSD)?

A

Number of pathogenic cells required to cause active infection in 50% of innoculated animals

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14
Q

What is median lethal dose (LDSD)?

A

Number of pathogen cells (or amount of toxin) requires to kill 50% of infected animals

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15
Q

What is on the X axis of a pathogenicity graph?

A

The number of pathogenic agents (cells or virons)

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16
Q

What is the Y axis of a pathogenicity graph?

A

The percentage morality in experimental group

17
Q

What does a pathogenicity graph show?

A

The percentage of aimals that have been infected (IDSD) or killed (LDSD) is plotted against the concentration of pathogen inoculate

18
Q

How can virulence change?

A

Attenuation

19
Q

What is attenuation?

A

The loss or decrease in virulence of a pathogen
When kepts in a lab culture vs isolated from diseased animal

20
Q

Do weakly virulent strains grow more quickly?

A

Yes

21
Q

Why is it important to know which pathogen is responsible for an infection?

A

Prescribe effective treatments
Eradicate the infection
Accurate records for infection control
Prevent further infections

22
Q

Who is Robert Koch?

A

founder of modern bacteriology
Invented the concept of infectious disease

23
Q

How do we know that a specific pathogen is responsible for an infection?

A

Each of Koch’s postulates represents a criterion that must be met before a disease can be positively linked with a pathogen

24
Q

What is number 1 of Kochs postulates?

A

The suspected causative agent must be absent from all healthy organisms but present in all diseased organisms

25
Q

What is number 2 of Kochs postualtes?

A

The causative agent must be isolated from the diseased organism ans grown in pure culture

26
Q

What is munber 3 of Kochs postulates?

A

The cultured agent must cause the same disease when inoculated into a healthy, susceptible organism

27
Q

What is number 4 of Kochs postulates?

A

The same causative agent must then be reisolated from the inoculated, diseased organism

28
Q

What are the limitations of Kochs number 1 postuate?

A

Assumes that pathogens are only found in diseased, not healthy individuals
Not absent from from healthy cells

29
Q

What are the limitations of Kochs number 2 postuate?

A

Not all pathogens can be grown in pure culture
Only grow when inside a host cell, postulate 2 not met

30
Q

What are the limitations of Kochs number 3 postuate?

A

Many human infections cannot be replicated in animal hosts
Do not cause infection
Cannot meet postulate 3

Biology + Microbiology (18 decks)

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