5. Staph Aureus

Question 1

What are the reasons staph aureus is clinically relevant?

Answer 1

Most virulent of the staph species
Remains a major cause of morbidity and mortality
Causes healthcare associated and community based infections

Question 2

How does staph aureus cause disease?

Answer 2

Causes disease through toxin mediated and non toxin mediated mechanisms

Question 3

Who is susceptible to colonisation

Answer 3

Insulin dependent diabetes,

HIV infection,

patients undergoing haemodialysis,

individuals with skin damage

Question 4

How are staph aureus infections classified?

Answer 4

Healthcare acquired or community acquired

Question 5

What are the different types of staph aureus infections?

Answer 5

Skin and sift tissue infections- staph aureus is the most commonly identified agent

Localised pyogenic staphylococcal infections- furuncles and carbuncles

Deep seated abscesses, necrotisng fascitis, pyomosistis

Osteomyeltis, septic arthritis, discitis

Infective endocarditis

Pneumonia, empyema

In the hospital setting wound infection and catheter associated infection

Question 6

What are frequent sites of staph aureus metastasis?

Answer 6

Bones and joints (esp when prostetic materials are present)
Epidural space and intervertebral discs
Native and prosthetic cardiac valves
Visceral abscesses in spleen, kidneys and lungs

Question 7

How can you investigate staph aureus infections?

Answer 7

Microscopy cultures of specimens make multiple blood cultures before commencing antibiotic regime

Repeat blood cultures are recommende 48-72 hours after commencing antimicrobial therapy

Biopsy samples may be of value for bone infections

Imaging, x-ray, CT, MRI, Radionuclide imaging

Transthoracic echocardiography

Question 8

How do you treat staph aureus?

Answer 8

Antibiotic therapy,

Source identification and clearance

Appropriate surgical intervention

Question 9

What antibiotics can be used to manage staph aureus

Answer 9

Fluxcloxacillin- minimum duration 14 days

Vancomycin- not ideal

Teicoplanin- single daily dosing or three times weekly

Linezolid- good bone penetration and excellent oral bioavailibity

Daptomycin- Cyclic lipopeptide with rapid bacterial activity against s aureus. well tolerated

Question 10

Where do staph aureus infections occur?

Answer 10

Skin (esp damaged),

vagina,

axilla,

perineum and oropharynx.

The colonisation sites serve as a reservoir for future infections