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Food-Borne Pathogens > Intoxications > Flashcards

Intoxications Flashcards

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1
Q

Foodborne intoxication

A

Occurs from ingestion of a food containing a preformed toxin

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2
Q

Why have S. aureus outbreaks decreased

A

Better use of refrigeration and improved sanitary practices

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3
Q

S aureus key features

A
  • Gram positive
  • Cocci
  • Non-motile, noncapsular
  • Non-spore forming
  • Heat sensitive
  • Facultative anaerobes
  • Mesophiles
  • Low Aw
  • Low pH
  • Poor competitors
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4
Q

How many housekeeping genes are found in S aureus

A

7

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5
Q

If a group of sequence types share at least 5-7 alleles, they can be defined as…

A

A clonal complex

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6
Q

Explain the restriction modification system of S. aureus

A

The accessory genome has a lot of mobile genetic elements that can be transferred horizontally, but the system prevents HGT from happening between clonal complexes

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7
Q

Phage genomes of S. aureus have…

A

Enterotoxins

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8
Q

Enterotoxin

A

Acts on GI tract

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9
Q

Endotoxin

A

Structurally associated with bacterial LPS

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10
Q

Exotoxin

A

Usually secreted into ECF, can be intracellular or injected into eukaryotic cells

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11
Q

Exfoliative toxins

A

Dermolytic exotoxins produced exclusively by S. aureus that cause impetigo or scaled skin syndrome

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12
Q

All Sa enterotoxins are…

A

Exotoxins

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13
Q

What toxins cause TSS

A

F (endotoxin) and B

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14
Q

When are toxins made in S. aureus

A

Exponential growth phase

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15
Q

Enterotoxin production can be inhibited by…

A

Glucose

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16
Q

How much of the gut does Sa carrying the enterotoxin gene inhabit

A

50% of non-enteritis patients

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17
Q

What is the main source of environmental Sa

A

Humans

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18
Q

What does Sa infection cause in cows

A

Mastitis

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19
Q

What can happen when humans carrying Sa infect animals

A

Repeated exposure causes human strains to adapt to animals, which can eventually reinfect humans
However the strains are unknown to humans so they may be more pathogenic

20
Q

Common foods contaminated with Sa

A

Ground beef, salmon, oyster, ground turkey

21
Q

Infectious dose of Sa toxin

A

1ng/g (less than 10^5cells/g)

22
Q

Four faces of C botulinum

A

Intoxication, infant botulism, wound botulism, bioterrorism

23
Q

Infant botulism

A

Ingestion and intestinal proliferation of the organism, internal production of toxin

24
Q

Wound botulism

A

Deep wound results in anaerobic environment

25
Q

How is C botulinum defined

A

All strains are toxic

26
Q

Cb group 3 toxins

A

Type C and D (animal)

27
Q

Cb group 2 toxins

A

Type E, non-proteolytic B and F

28
Q

Cb group 4 toxins

A

Type G

29
Q

Cb group 1 toxins

A

Type A, proteolytic B and F

30
Q

Nonproteolytic BoNT

A

Stomach acid cleaves it to activate

31
Q

Proteolytic BoNT

A

Bacteria produce a protease that activates it

32
Q

Which BoNT toxin types interfere with SNARE protein formation

A

B, D, F, G

33
Q

What BoNT toxin types interfere with membrane fusing

A

A, C, E

34
Q

What BoNT toxin type interferes with release of neurotransmitter

A

C

35
Q

What Cb strains infect humans

A

Group 1 and 2

36
Q

Why is trypsin added in Cb detection

A

To determine if it is proteolytic or non proteolytic

37
Q

The BoNT toxin can be carried on…

A

A chromosome or plasmid

38
Q

Describe the Cb genome

A

Circular chromosome, G/C content of 27-28%

39
Q

What is a major concern of the mobility of the BoNT toxin genes

A

C. difficile getting it through HGT

40
Q

Where is Cb found

A

Ubiquitous in soils

41
Q

How does Cb survive

A

Secretes hydrolytic enzymes and then transports the stuff it degrades into the cell (does not have own genes for AA synthesis)

42
Q

If Cb is ubiquitous, how come a lot of people are not infected

A

It is outcompeted by other organisms so it can’t produce to toxin

43
Q

What is a common cause of food botulism

A

Home canning of fruits and veggies and fermented fish

44
Q

What toxin types are associated with fish

A

E

45
Q

What toxin types are associated with fruits and vegetables

A

A and B

Food-Borne Pathogens (14 decks)

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