PowerPoint 5:Staphyloccocus Aureus

Question 1

How does food intoxication occur?

Answer 1

Ingestion of food which had a pre-formed toxin

Question 2

Do symptoms occur quickly?

Answer 2

Yes, usually 30 min after ingestion

Question 3

Are febrile symptoms present?

Answer 3

No

Question 4

Is it motile?

Answer 4

No

Question 5

Does it have a capsule?

Answer 5

No

Question 6

Does it have form spores?

Answer 6

No

Question 7

Is it sensitive to heat treatments?

Answer 7

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

Question 8

What is their aerobic classification?

Answer 8

Facultative aerobes.

Grow better in oxygen.

Question 9

What is their “temperature” classification?

Answer 9

Mesophiles

Question 10

What temperature can Staph grow at?

Answer 10

7°C - 48°C

Question 11

What temperature can they rapidly grow at?

Answer 11

20°C-37°C

Question 12

What Aw can they grow at?

Answer 12

Low (0.86)

Question 13

What pH can they grow at?

Answer 13

Low (pH 4.8)

Question 14

What salt and sugar concentrations can it grow at?

Answer 14

High salt and sugar concentrations

Question 15

Can they grow under adverse conditions?

Answer 15

Yes

Question 16

Are they good competitors against other organisms?

Answer 16

No

Question 17

What illnesses can it cause?

Answer 17

Skin infections
Endocarditis 
Toxic shock syndrome
Necrotizing pneumonia
Mastitis

Question 18

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

Answer 18

20%

Question 19

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

Answer 19

T

Question 20

How many prophage genomes are carried?

Answer 20

1-4

Question 21

Where are the enterotoxins found?

Answer 21

Phage genome

Question 22

Is illness caused by ingestion of the organism?

Answer 22

No

Question 23

What is an endotoxin?

Answer 23

Toxin associated structurally with the bacterial cell (LPS)

Question 24

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

Answer 24

Yes, but it is secreted by the bacteria producing it

Question 25

What are exfoliative exotoxins?

Answer 25

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

Question 26

T/F All enterotoxins are also exotoxins

Answer 26

T

Question 27

what type of eneterotoxin does it produce?

Answer 27

A B C D E F G H I J

Question 28

What is the toxin that causes toxic shock syndrome?

Answer 28

Endotoxin F | Enterotoxin B

Question 29

In what phase are the enterotoxins formed?

Answer 29

Exponential growth phase

Question 30

What can inhibit the production of enterotoxins?

Answer 30

Glucose

Question 31

Are enterotoxins involved in Quorum Sensing?

Answer 31

Yes probably

Question 32

Why is staph. aureus toxin special?

Answer 32

Very heat stable - not destroyed by boiling or canning

Question 33

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

Answer 33

50%

Question 34

What does the toxin stimulate?

Answer 34

Vagus and sympathetic nerves

Question 35

Who are the main reservoir?

Answer 35

People

Question 36

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

Answer 36

T

Question 37

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

Answer 37

Yes

Question 38

Can it be resistant to metals and antibiotics?

Answer 38

Yes

Question 39

Is it able to survive a variety of extreme environments?

Answer 39

Yes

Question 40

What disease can it cause in cows?

Answer 40

Bovine mastitis

Question 41

What is the optimal temperature for their growth?

Answer 41

37-40 degress celsius

Question 42

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

Answer 42

3 hours

Question 43

Does it have a quick onset?

Answer 43

Yes, 30 minutes

Question 44

How long does it take for recovery?

Answer 44

12-48 hours

Question 45

Is it self-limiting?

Answer 45

Yes

Question 46

Is there any fever?

Answer 46

No

Question 47

What is the purified toxin considered?

Answer 47

Bio terrorism agent

Question 48

What is the infectious dose?

Answer 48

10^5 cells / g

Question 49

What is the infectious dose of the toxin?

Answer 49

1 ng/g

Question 50

Some strains are resistant to what?

Answer 50

Methicillin-Resistant Sa (MRSA) | -carry the macA gene

Question 51

What disease does MRSA cause?

Answer 51

- soft tissue and skin infections | - necrotizing fascitis

Question 52

Summary

Answer 52

- 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