Staph Aureus Bacteraemia

Question 1

How does Staph aureus cause disease?

Answer 1

Toxin and non-toxin mediated mechanisms

Question 2

How does Staph aureus appear on stain?

Answer 2

Gram-positive cocci that form grape-like clusters on Gram stain

Question 3

How common in colonisation in healthy persons?

Answer 3

25-50%

Question 4

Which factors increase the likelihood of staph aureus colonisation?

Answer 4

T2DM
HIV infection
Haemodialysis
Skin damage

Question 5

What is the most common site of staph aureus colonisation?

Answer 5

Nostrils
Skin
Vagina
Axilla
Perineum
Oropharynx

Question 6

How are Staph aureus blood stream infections classified?

Answer 6

Healthcare or community acquired

Primary or secondary

Question 7

How do localised pyogenic staphylococcal infections present?

Answer 7

Furuncles

Carbuncles

Question 8

1/3 S. aureus bacteraemia patients develop what?

Answer 8

Local complications

Distant septic metastases

Question 9

What are the most common sites of S. aureus bacteraemia metastases?

Answer 9

Bones/joints (esp. prosthetics)
Epidural space
Intervertabral discs
Native/prosthetic valves
Cardiac devices
Abscesses in spleen/kidneys/lungs

Question 10

How should S. aureus bacteraemia be investigated?

Answer 10

Microscopy
Culture of specimens
Multiple blood cultures before antibiotics (48-72hrs)
Biopsy for bone infections
Imaging 
Transthoracic Echo

Question 11

How should S. aureus bacteraemia be managed?

Answer 11

Antibiotics
Source identification and clearance
Surgical intervention

Question 12

Which antibiotics should be used for S. aureus bacteraemia?

Answer 12

Flucloxacillin - 14 days 
Vancomycin (poor)
Teicoplanin
Linezolid
Daptomycin