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Foodborne Pathogens > PowerPoint 5:Staphyloccocus Aureus > Flashcards

PowerPoint 5:Staphyloccocus Aureus Flashcards

1
Q

How does food intoxication occur?

A

Ingestion of food which had a pre-formed toxin

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2
Q

Do symptoms occur quickly?

A

Yes, usually 30 min after ingestion

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3
Q

Are febrile symptoms present?

A

No

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4
Q

Is it motile?

A

No

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5
Q

Does it have a capsule?

A

No

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6
Q

Does it have form spores?

A

No

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7
Q

Is it sensitive to heat treatments?

A

Yes.
66°C for 12 minutes
72°C for 15 seconds

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8
Q

What is their aerobic classification?

A

Facultative aerobes.

Grow better in oxygen.

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9
Q

What is their “temperature” classification?

A

Mesophiles

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10
Q

What temperature can Staph grow at?

A

7°C - 48°C

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11
Q

What temperature can they rapidly grow at?

A

20°C-37°C

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12
Q

What Aw can they grow at?

A

Low (0.86)

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13
Q

What pH can they grow at?

A

Low (pH 4.8)

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14
Q

What salt and sugar concentrations can it grow at?

A

High salt and sugar concentrations

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15
Q

Can they grow under adverse conditions?

A

Yes

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16
Q

Are they good competitors against other organisms?

A

No

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17
Q

What illnesses can it cause?

A 
Skin infections
Endocarditis 
Toxic shock syndrome
Necrotizing pneumonia
Mastitis
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18
Q

What percentage of the S. aureus genome is made of mobile genetic elements that can be transferred ?

A

20%

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19
Q

T/F : Enterotoxin is mainly found in mobile genetic elements?

A

T

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20
Q

How many prophage genomes are carried?

A

1-4

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21
Q

Where are the enterotoxins found?

A

Phage genome

22
Q

Is illness caused by ingestion of the organism?

A

No

23
Q

What is an endotoxin?

A

Toxin associated structurally with the bacterial cell (LPS)

24
Q

Can an exotoxin be intracellular and injected directly into a eukaryotic cell?

A

Yes, but it is secreted by the bacteria producing it

25
Q

What are exfoliative exotoxins?

A

dermolytic exotoxin produced exclusively by s. aureus and causes impetigo or scaled skin.

26
Q

T/F All enterotoxins are also exotoxins

A

T

27
Q

what type of eneterotoxin does it produce?

A

A B C D E F G H I J

28
Q

What is the toxin that causes toxic shock syndrome?

A

Endotoxin F

Enterotoxin B

29
Q

In what phase are the enterotoxins formed?

A

Exponential growth phase

30
Q

What can inhibit the production of enterotoxins?

A

Glucose

31
Q

Are enterotoxins involved in Quorum Sensing?

A

Yes probably

32
Q

Why is staph. aureus toxin special?

A

Very heat stable - not destroyed by boiling or canning

33
Q

How many patients (in percentage) carry s. aureus with enterotoxin genes yet they don’t get the disease?

A

50%

34
Q

What does the toxin stimulate?

A

Vagus and sympathetic nerves

35
Q

Who are the main reservoir?

A

People

36
Q

T/F It can be passed by direct contact and respiratory droplets

A

T

37
Q

Is Staph. aureus able to invade our cells and live intracellularly?

A

Yes

38
Q

Can it be resistant to metals and antibiotics?

A

Yes

39
Q

Is it able to survive a variety of extreme environments?

A

Yes

40
Q

What disease can it cause in cows?

A

Bovine mastitis

41
Q

What is the optimal temperature for their growth?

A

37-40 degress celsius

42
Q

How many hours does it require to produce sufficient toxins in the ideal temperature?

A

3 hours

43
Q

Does it have a quick onset?

A

Yes, 30 minutes

44
Q

How long does it take for recovery?

A

12-48 hours

45
Q

Is it self-limiting?

A

Yes

46
Q

Is there any fever?

A

No

47
Q

What is the purified toxin considered?

A

Bio terrorism agent

48
Q

What is the infectious dose?

A

10^5 cells / g

49
Q

What is the infectious dose of the toxin?

A

1 ng/g

50
Q

Some strains are resistant to what?

A

Methicillin-Resistant Sa (MRSA)

-carry the macA gene

51
Q

What disease does MRSA cause?

A
  • soft tissue and skin infections

- necrotizing fascitis

52
Q

Summary

A
  • toxins are an important factor
  • reside on skin, nare, and hair of humans and animals
  • any foodstuff involving human contact, or is from a food producing animal can be potentially infected
  • the result of the Sa contamination will depend on the genetic makeup of the particular organism

Foodborne Pathogens (11 decks)

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