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Food-Borne Pathogens > Toxico-infections > Flashcards

Toxico-infections Flashcards

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1
Q

Common characteristics among spore forming toxico-infections

A
  1. Ingestion of large numbers of live vegetative cells

2. Vegetative cells of spore formers do not multiply in the GI tract (sporulate and release toxins)

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2
Q

Common characteristics among gram-negative bacteria toxico-infections

A
  1. Live cells are ingested in moderate numbers
  2. Gram negative cells rapidly multiply in GI tract
  3. Many cells die, releasing toxins
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3
Q

What is the growth temp of C. perfingens

A

10-52C, optimal at 45C

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4
Q

Why do C. perfringens grow on high protein foods

A

They lack amino acid synthesis ability

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5
Q

What are the 4 most important factors contributing to an outbreak of C. perfringens

A
  1. Cooking in large volumes in advance
  2. allowing it cool slowly
  3. holding for a long period of time
  4. serving without reheating
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6
Q

Describe a C. perfringens outbreak

A
  1. cooking kills vegetative cells, spores survive
  2. Large volumes of food provide anaerobic environment
  3. Slow cooling allows spores to germinate and multiply
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7
Q

Where are C. perfringens vegetative cells founds

A

Soil, dust, intestines of food-producing animals, birds

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8
Q

When do C. perfringens symptoms appear

A

8-24 hours (resolve in 24 hours)

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9
Q

What are symptoms of C. perfringens infection

A

Diarrhea, abd pain, nausea, vomiting

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10
Q

What is the virulence potential of C. perfringens based on

A

The ability of Cp to produce various combinations of more than 15 different toxins and several extracellular hydrolytic enzymes

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11
Q

What are the 5 toxinotypes of Cp and what are they based on

A

A,B,C,D and E

They are based on the production of 4 major toxins (alpha, beta, epilson, iota)

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12
Q

When are Cp toxins secreted

A

Exponential growth phase

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13
Q

What Cp strains are associated with food poisioning

A

Type A

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14
Q

What are 2 ways Cp toxins make conditions to favor infection

A
  1. Disrupt host cell membranes to release nutrients

2. Hydrolytic enzymes break down complex nutrients into smaller units that can be imported into the cell

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15
Q

What Cp toxin is responsible for the GI symptoms

A

CPE (enterotoxin, only produced during sporulation)

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16
Q

How does CPE work

A

It binds enterocytes and creates pores that cause the release of large volumes of water and nutrients

17
Q

What allows Cp to spread in the environment

A

When it sporulates in the intestine, diarrhea ensures it is passed into the environment

18
Q

What needs to happen for gastroenteritis to occur in Cp infection

A

Viable cells must be present in high numbers

19
Q

4 Prevention methods of Cp infection

A

Proper sanitation, cooking food to highest temp possible, food should be cooled quickly and uniformly, food stored for a long time should be re-heated quickly and kept above 60C during serving

20
Q

Where is Bc isolated from

A

soil and growing plants, raw milk (from grass contamination, can survive pasteurization)

21
Q

At what temp can Bc not be grown

A

Below 10C (although some can grow in as low as 4C)

22
Q

Why does Bc contaminated milk rarely cause illness

A

The proteases produced by Bc cause off flavors and people don’t consume a lot

23
Q

What are the two toxins of Bc

A

Emetic (vomit-inducing) and diarrheal enterotoxin

24
Q

How does the emetic toxin stimulate vomiting

A

It stimulates the vagus nerve

25
Q

How does the diarrheal enterotoxin stimulate diarrhea

A

By stimulating cAMP system

26
Q

Describe the infection process of Bc

A

Cooking kills the vegetative cells, the spores survive, spores are able to germinate and proliferation
**If vegetative cells are present, Bc isn’t competitive

27
Q

4 factors that contribute to Bc illness

A

Improper holding temp
Contaminated equipment
Inadequate cooking
Poor personal hygiene

28
Q

How to present Bc spore germination

A

Uniform quick chilling of food to 4C, or holding food above 60C (since some can grow at 4C , food should not be refrigerated for long periods of time)

29
Q

B. anthracis

A

Cause of acute and lethal disease, anthrax

30
Q

B. thuringiensis

A

Biological control of insects, because of its ability to produce protein crystals with insecticidal activity

31
Q

B. cereus

A

Causes food borne illness, some strains have been developed as bio control agents in the suppression of fungal and crop diseases

32
Q

What Bacillus strains are essentially the same based on phylogenetic studies

A

B. thuringiensis and B. cereus (emetic type)

33
Q

What foods are associated with the diarrheal toxin

A

Desserts, meat and dairy

34
Q

What foods are associated with the emetic toxin

A

Rice and pasta

35
Q

What is the defining feature for V. cholera and ETEC to be toxicoinfections

A

Large numbers of cells must be ingested for symptoms

Food-Borne Pathogens (14 decks)

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