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16 Cards in this Set

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  • Back
What is unique about S. aureus toxin?
It is not destroyed by heating or canning
Name characteristics of S. aureus
Cocci shaped, organized in clusters, gram +, catalase positive, mannitol salt fermentation +, (s.aureus)coagulase +, non sporeforming, facultative anaerobe, non-motile, enterotoxin +, hemolysis +, thermostable DNAse, Yellow colonies,
What are the diseases caused by S. aureus?
Skin infections (pimples, impetigo), nosocomial infections, respiratory infections, toxic shock syndrome, endocarditis (inside organs), foodbourne intoxications, halotolerant (up to 10% -- most of any pathogen), can grow in Aw of 0.86, phychrophile
What are the disease characteristics of S. aureus?
food intoxication, 1-6 hour incubation time, 10>5 CFU/g infectious dose, nausea, severe vomiting, severe abdominal cramps, diarrhea, NOOO FEVER!, Self limiting
Virulence Factors for S. aureus
Composed of Two Subunits (C-Terminal causes emesis)

Many Different Types: A, b, c1, c3, c3, d, e, g, h, i, j (named in order of discovery)

Belong to superantigen group of toxins

Extremely resistant to heat, pH and proteolysis

Toxin dose is 1 ng

Affected Cells:
Neural receptors in abdomen
Intestinally Associated Immune Cells
Where can S. aureus be found in nature?
Nose, throat and skin of Humanoids

Warm bloded animals (Low #'s)

Persist in air, dust and equipment in food processing environment

What are associated foods with Staph aureus infection?
Deli meat, fermented foods, ham, salads (potato, turkey, chicken), tacos, burritos, canned mushrooms, smoked oysters, dairy
What foods have highest prevalence of Staph aureus?
Blue crabmeat, Big game, pork sausage, deli salads
Name selective agents in S. aureus culture testing
Potassium Tellurite, LiCl
Name differential ingredients in S. aureus culture testing.
Potassium tellurite, Egg yolk (halo and precip)
How can S aureus be controlled so taht it does not produce enterotoxin?
Prevent growth by keeping food below 5C or above 50C

Good GMP/personal hygeine

Monitor pH of fermented foods ot ensure active fermentation

If staph is used as starter culture, make sure it is enterotoxin free
What are confirmatory steps in S. aureus detection?
Coagulase and thermonuclease test
What is special about toxic shock syndrome toxin?
It is considered an exotoxin that does not cause vomiting as the other toxins do. It is called Toxic shock syndrome toxin 1
Which enterotoxin strain produces the greatest amount of toxin? Easiest to detect? Which go undetected the most?
B and C produce the most in amount up to 350µg/mL

A, D, and E are easily detected by PFGE

D & J go undetected the most
What genes regulate expression of the enterotoxin?

Which strain is not regulated by agr (most common)?
agr (expressed differently by each strain) acessory gene regulator, sar (staph acessory regulator), and sae (s aureus exoprotein expression)

Strain A is not regulated by agr, which is why it is expressed prior to the other enterotoxins.
The enterotoxins are mostly expressed during what phase?
Late exponential and post exponential growth