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The Public (Y2) > Pathogens and the host: variously invasive pathogens > Flashcards

Pathogens and the host: variously invasive pathogens Flashcards

1
Q

How can virulence be measured?

A

From experiemental studies - lethal dose
Highly virulent pathogens show little difference in number of cells needed to kill 100% of population compared to 50% of population

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2
Q

What is meant by lethal dose?

A

Lethal dose is the amount of agent that kills 50% of

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3
Q

What is meant by attenuation?

A

the decrease or loss of virulence

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4
Q

What is meant by invasiveness?

A

ability of pathogen to grow in host tissues at densities that inhibit host function - without producing toxin

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5
Q

Toxicity is means of causing damage to host via production of toxin. True or false?

A

True

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6
Q

Non-invasive pathogens involve viable bacteria but no penetration through epithelial layer. True or false?

A

True

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7
Q

Is diptheria an invasive or non-invasive pathogen?

A

Non-invasin

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8
Q

Diptheria bacteria are gram negative. True or false?

A

False - gram positive

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9
Q

Non-invasive pathogens are localised at point of entry or mediated by exotoxins. True or false?

A

True

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10
Q

Explain the pathogenisis of diptheria

A

Inhalation of aerosol - colonisation in throat
Produces single chained A-B toxin
Psuedomembrane forms in throat and A-B toxin inhibits elongation factor 2 in eukaryotic cells. This inhibits protein synthesis and therefore kills cell

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11
Q

Is pertussis bacteria are gram positive. True or false?

A

False - gram negative

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12
Q

DIptheria causes difficulty swallowing. True or false?

A

True

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13
Q

Explain the pathogenisis of pertussis bacterium.

A

attached and replicate on ciliated upper respiratory tract mucosa
toxin production: pertussis exotoxin, trachael cytotoxin, invasive adenylate cyclase toxin
these cause loss of mucociliary clearance, violent coughing fits and secondary pneumonia

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14
Q

How many toxins does the pertussis bacterium produce?

A

3

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15
Q

Is pertussis bacterium invasive or non-invasive?

A

Non-invasive

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16
Q

Is cholera bacterium gram positive or negative?

A

gram negative

17
Q

Explain the pathogenisis of cholera bacterium

A

Acute infection of GIT (small intestine)
production of cholera toxin - causes upregulation of adenylate cyclase and loss of fluid from GIT -> death through dehydration (unless prevented by rehydration therapy)

18
Q

What is meant by a partially-invasive pathogen?

A

Invade epithelial layer but don’t penetrate deeper tissue. They invade at primary site of infection only

19
Q

Are shigella bacteria gram positive or negative?

A

Negative

20
Q

Do shigella bacteria form spores?

A

No

21
Q

What is the clinical presentation of shigellosis?

A

Blood and puss in diarrhoea

22
Q

Explain the pathogenisis of shigella bacteria

A

attachment and invasion of ileum and colonic epithelia
produces A-B toxin
invasion is no deeper than lamina propria

23
Q

Invasive pathogens cause minimum damage at primary site of infection. True or false?

A

True

24
Q

How do invasive pathogens spread to lymphatics?

A

via lymph

25
Q

Is enteric fever caused by an invasive or non-invasive pathogen?

A

Invasive

26
Q

How is enteric fever transmitted?

A

Person-person or through consumption of contaminated food

27
Q

Enteric fever can be spread by animal reservoir. True or false?

A

False

28
Q

Explain the pathogenesis of enteric fever bacterium.

A

Bacterial induced uptake via M cells - travel through epithelia and cause systemic dissemination

29
Q

In food poisoning, is bacterial colonisation present?

A

No

30
Q

Food poisoning occurs on consumption of food contaminated with toxins of chemical or bacterial origin. True or false?

A

True

31
Q

Which bacteria causes botulism?

A

Clostridium botulinum

32
Q

Clostridium botulinum is gram positive. True or false?

A

True

33
Q

The botulinum bacteria is spore forming. True or false?

A

True

34
Q

Staphylococcus aureus can cause skin infections and food poisoning. True or false?

A

True

35
Q

How are symptoms produced by staph. aureus?

A

the bacteria produces an enterotoxin - toxin is ingested and interacts with gastric mucosa - symptoms

36
Q

Bacillus cereus doesn’t form spores. True or false?

A

False

37
Q

What are the two disease forms of bacillus cereus?

A

emetic toxin - heat stable, short incubation

enterotoxin - heat labile, longer incubation

The Public (Y2) (35 decks)

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