S.aureus bacteraemia

Question 1

What type of bacteria is staphylococci?

Answer 1

Gram positive cocci

Question 2

What do clusters of staphylococci look like on gram stain?

Answer 2

Grape-like clusters

Question 3

What is the most virulent of the staphylococcal species?

Answer 3

Staphylococcus aureus

Question 4

Is staphylococcus aureus responsible for HAI or community based infections?

Answer 4

Both

Question 5

S.aureus is part of the normal human flora: true or false?

Answer 5

True

Question 6

S.aureus causes disease through which mechanisms?

Answer 6

Toxin-mediated

Non-toxin mediated

Question 7

What percentage of healthy persons may be persistently or transiently colonised with S.aureus?

Answer 7

25-50%

Question 8

Which patients are most at risk of colonisation of S.aureus?

Answer 8

Insulin-dependent diabetes
HIV infection
Patients undergoing haemodialysis
Patients with skin damage

Question 9

Where is the most frequent site of S.aureus colonisation?

Answer 9

Anterior nares

Question 10

Where are sites which S.aureus commonly colonises?

Answer 10

Anterior nares
Skin
Vagina
Axilla
Perineum
Oropharynx

Question 11

Why are colonisation sites of S.aureus important?

Answer 11

Serve as reservoir for future infections

Question 12

Persons colonised with S.aureus are at greater risk of subsequent infection than uncolonised individuals: true or false?

Answer 12

True

Question 13

How are S.aureus blood stream infections traditionally classified?

Answer 13

By environment of acquisition: healthcare associated or community acquired

Question 14

With what type of infections is S.aureus the most commonly identified agent?

Answer 14

Skin and soft tissue infections

Question 15

What is another word for a furcuncle?

Answer 15

A boil

Question 16

What are furuncles and carbuncles?

Answer 16

Localised pyogenic staphylococcal infections

Question 17

What is a carbuncle?

Answer 17

A cluster of boils

Question 18

What type of infections in hospital may be caused by S.aureus?

Answer 18

Wound infection, vascular line, catheter-related infection

Question 19

What are frequent sites of distant metastases of S.aureus bacteraemia?

Answer 19

Bones and joints (esp prosthetics)
Epidural space and IV discs
Native and prosthetic cardiac valves/cardiac devices
Visceral abscesses in spleen, kidneys and lungs

Question 20

What investigations would you do for suspected S.aureus infections?

Answer 20

Microscopy and culture of specimens
Multiple blood cultures
Repeat blood cultures after commencing antimicrobial therapy
Biopsy samples (bone infections)
Imaging: X-ray, CT, MRI, radionuclide imaging
Transthoracic echocardiography, TOE

Question 21

What is the basis of treatment for invasive staphylococcal infections?

Answer 21

Antibiotic therapy
Source identification and clearance
Appropriate surgical intervention

Question 22

What has been associated with an increased risk of complications and higher mortality in S.aureus infections?

Answer 22

Delay in the administration of appropriate antibiotic therapy and persistent bacteraemia

Question 23

What antibiotics are indicated for S.aureus infections?

Answer 23

Flucloxacillin
Vancomycin
Teicoplanin
Linezolid
Daptomycin

Question 24

What is the minimum duration of treatment for uncomplicated S.aureus bacteraemia with flucloxacillin?

Answer 24

14 days

Question 25

Why is vancomycin not the ideal drug to use for a sensitive S.aureus infection?

Answer 25

Poor tissue penetration, slow bactericidal activity, inconvenient administration and side effects

Question 26

Why is teicoplanin a good antibiotic for S.aureus infections?

Answer 26

Single daily dosing and use three times weekly after appropriate loading

Question 27

Why is linezolid a good antibiotic for S.aureus infections?

Answer 27

Bacteriostatic, synthetic oxazolidinone, good penetration into bone and excellent oral bioavailability

Question 28

Why is daptomycin a good antibiotic for S.aureus infections?

Answer 28

Rapid bactericidal activity against S.aureus, well tolerated, once daily dosing

Question 29

What is the first line treatment for MSSA?

Answer 29

Flucloxacillin

Question 30

What type of administration is flucloxacillin for S.aureus infection?

Answer 30

IV

Question 31

What is the first line treatment for MRSA?

Answer 31

Vancomycin

Question 32

47yr old lady IVDU, 5 day history fever, cough, SOB. Painful swollen right groin. Alert and orientated. 90% O2 on air. Pyrexial at 38.5C. BP 110/60. 110HR. 32RR. Bloods: WCC 31.9, urea 8 Doppler US DVT? infected right leg What organism likely to be responsible for CXR findings? Antibiotics commence on?

Answer 32

Staph aureus | IV flucloxacillin

Question 33

Blood cultures positive for S.aureus. 2wks therapy, ongoing cough, fever, right sided chest discomfort and right groin pain/discharge. Bloods: WCC 18, CRP 210 Which investigations? What does CXR show?

Answer 33

ECHO CXR Repeat blood cultures US groin Post-pneumonic effusion