Staph aureus

Question 1

Classified according to the environment of acquisition and the absence or presence of identified associated sites of infection

Answer 1

• healthcare associated or
• community acquired
• primary or
• secondary

Question 2

Staph aureus spectrum of infection

Answer 2

• Skin & Soft Tissue Infections- S. aureus is the most commonly identified agent.
• Localised pyogenic staphylococcal infections- furuncles and carbuncles.
• Deep-seated abscesses, necrotising fasciitis, pyomyositis
• Osteomyelitis, Septic arthritis, Discitis
• Infective endocarditis
• Pneumonia, Empyema

Question 3

What fraction of patients with Staph aureus bacteraemia develop local complications or distant septic metastases?

Answer 3

1/3

Question 4

Frequent sites of distant staph aureus metastases

Answer 4

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

Question 5

Staph aureus investigations

Answer 5

• microscopy and culture of specimens
• multiple blood cultures before commencing antibiotic therapy
• repeat blood cultures are recommended 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 (TOE)

Question 6

Basis of treatment for invasive staphylococcal infections

Answer 6

• Antibiotic therapy
• Source identification and clearance
• and appropriate surgical intervention

Question 7

Antibiotic management of Staph aureus

Answer 7

• Flucloxacillin
• Vancomycin
• Teicoplanin
• Linzolid
• Daptomycin

Question 8

Flucloxacillin

Answer 8

Minimum duration of treatment for uncomplicated Staph aureus bacteraemia is 14 days

Question 9

Vancomycin

Answer 9

far from an ideal drug due to poor tissue penetration, slow bactericidal activity, inconvenient administration and side effects

Question 10

Teicoplanin

Answer 10

has an advantage in terms of its single daily dosing and could also be used three times weekly after appropriate loading

Question 11

Linzolid

Answer 11

• bacteriostatic
• synthetic oxazolidinone
• good penetration into bone and excellent oral bioavailability

Question 12

Daptomycin

Answer 12

• cyclic lipopeptide with rapid bactericidal activity against Staph aureus
• well tolerated
• has the advantage of once daily dosing