Staphylococcus Flashcards
(22 cards)
Is aureus coagulase positive or negative?
Positive
How does staph intoxicate food?
Toxins bind to membrane to make oligomeric complexes around central pore
What does aureus do to humans?
Severe tissue damage
How do the toxins effect humans?
Toxic shock syndrome and food poisoning
What is scaled skin syndrome?
Exfoliative toxins causing blistering
Who does scaled skin syndrome effect?
Babies and children
What causes toxic shock syndrome?
TSST-1
Who does toxic shock syndrome effect?
Menstruating women using tampons or surgical infections
Symptoms of toxic shock syndrome
Peeling skin of palms and feet
How does aureus cause illness?
Intoxication
Does aureus carry enterotoxins?
Some carry >1 enterotoxin but not all strains are toxigenic
What are the enterotoxin types?
A, B, C1, C2, C3, D, E, G-Y
What are the properties of aureus toxins?
Single-chain proteins
Heat stable
pH stable
Resistant to stomach enzymes
Why are they classed as heat stable?
126C for 90mins needed to destroy them
What is the minimal toxic dose?
90ng
How do enterotoxins cause illness?
Neurotoxins activate receptors on the abdominal viscera
How do enterotoxins cause vomiting?
Stimulus reaches vomiting centre via vagus nerve
What are the symptoms of staph food poisoning?
Nausea
Vomiting
Cramps
Diarrhoea
Rarely fatal
How long do symptoms last?
Rapid onset lasts for 24h
Properties of staph
Growth at 7-48C
pH 4-9.8
>0.83 aw
5-7% salt
>100,000 cfu to cause disease
What are the conditions needed for toxin production?
10-45C
4.8-9 pH
>0.86 aw
What foods does staph effect?
Animal products
Salads
Skin of animals
