Staphylococcus Aureus

Question 1

What sort of diseases can it cause?

Answer 1

Skin and soft tissue infection: Cellulitis, wound infection
Resp: Pneumonia
Cardiovascular: Septicaemia, Endocarditis
UTI
Disease caused by toxins: Toxic shock syndrome, food poisoning

Question 2

What is toxic shock syndrome?

Answer 2

Superantigens can bind to T cells directly (As opposed to first binding a antigen-presenting cell)
Can cause massive activation of T cells
These T cells can produce a cytokine storm, causing ‘multisystem disease’

Question 3

What is the classic presentation of staph aureus?

Answer 3

You get characteristic pus filled boils and abscesses

Question 4

Gram positive/negative?

Answer 4

positive

Question 5

What shape is it?

Answer 5

coccus

Question 6

Where is it normally found?

Answer 6

Skin and mucousal membranes

Question 7

Name some virulence factors and what effect these have on the body

Answer 7

Cell wall virulence factors:
Capsule- Resistance to phagocytosis
Protein A- Antiphagocytic

Cytolytic exotoxins- attack cell membrane causing osmotic lysis

Superantigen exotoxin- Can cause Toxic shock syndrome since have affinity for T-cell receptor

Question 8

Describe some investigations that could test for this bacteria (3)

Answer 8

Gram stain- Purple, cocci, in clusters like grapes

Catalase positive

Coagulase positive(other staphylococci are negative)

Question 9

What treatment could be used to treat an infection caused by this bacteria?

Answer 9

Supportive: Drainage of localised tissue

Specific: Vancomycin (Resistant to pencillin)

Question 10

Describe some preventative measures

Answer 10

Infection control measures (eg handwashing)