Staph. Aureus Bacteraemias

Question 1

What type of bacteria is Staph Aureus?

Answer 1

Gram positive cocci

Question 2

Which bacteria is the most virulent* within the staphylococcal species?

*harmful

Answer 2

Staph Aureus

Question 3

How can S.aureus survive in the body?

Answer 3

Has an environment resistant peptidoglycan wall surrounded by a microcapsule
Produce a range of surface proteins involved in host colonisation, tissue invasion and also produce toxins

Question 4

Which toxins can S.Aurues produce?

Answer 4

Cytolytic toxins
Exfoliative toxins
Enterotoxins
TSST-1

Question 5

What do cytotoxins do?

Answer 5

Break down neutrophils releasing lysosomal enzymes in surrounding tissues

Question 6

What is Staphylococcal scaled skin syndrome?

Answer 6

A condition which is mediated by exfoliative toxins and characterised by exfoliative dermatitis

Question 7

Which symptoms are enterotoxins usually related to?

Answer 7

GI symptoms

Question 8

Which type of staphylococcal toxins is associated commonly with food poisoning?

Answer 8

Enterotoxins

Question 9

Which type of toxin is associated with toxic shock syndrome?

Answer 9

TSST-1

Question 10

Staph aureus is found in healthy humans as well, it makes up a part of the gut flora.
In which patient is the rate of colonisation higher?

Answer 10

In patients with:
-Insulin-dependant diabetes
-HIV
-Haemodialysis
-Skin damage

Question 11

Which part of the body is the most frequent site of colonisation?

Answer 11

Anterior nares (nose)

->skin, vagina, axilla, perineum and oropharynx may also be colonised

Question 12

What are the different classifications of S.Aurues blood stream infections?

Answer 12

Healthcare or community associated
Primary or secondary infections

Question 13

Which bone related infections is S.Aureus responsible for?

Answer 13

Osteomyelitis
Septic arthritis
Discitis

Question 14

Which skin related infections is S.Aureus responsible for?

Answer 14

Deep-seated abscesses
Necrotising fasciitis
Pyomyositis

Question 15

Which cardio related infections is S.Aureus responsible for?

Answer 15

Infective endocarditis

Question 16

Which lung related infections is S.Aureus responsible for?

Answer 16

Pneumonia
Empyema

Question 17

Approximately 1/3 of patients with staph aureus bacteremia develop local complications or distant metastatic complications.

Where are some of the frequent sites of distant metastases?

Answer 17

Bones and joints, especially where prosthetic materials are present
Epidural space and IV discs
Native and prosthetic cardiac valves, cardiac devices
Visceral abscesses in spleen, kidneys and lung

Question 18

Which investigations are used to investigate S.Aureus infections?

Answer 18

Microscopy and culture of specimens
Biospy samples for bone infections
XR, CT, MRI depending on issue
Transthoracic ECHO

Question 19

What is important to note about blood cultures?

Answer 19

Multiple required before commencing antibiotic therapy

Recommended to repeat cultures 48-72hrs after commencing antimicrobial therapy

Question 20

Which imaging is bets for bone infections like osteomyelitis?

Answer 20

Xray

Question 21

Which imaging is best to look for abscesses?

Answer 21

CT

Question 22

Which imaging is best for looking for any spine infections?

Answer 22

MRI

Question 23

What is the management of S.Aureus infections?

Answer 23

Antibiotic therapy
Source identification and clearance
Any appropriate surgical intervention

Question 24

Okayyyy…antibiotic management xx

What is the minimum duration of treatment of flucloxacillin for an uncomplicated S.Aureus infection?

Answer 24

14 days

Question 25

Okayyyy...antibiotic management xx Why is Vancomycin a poor choice of antibiotic for S.Aureus infection?

Answer 25

Poor tissue penetration Slow bactericidal activity Inconvenient administration Adverse side effects

Question 26

Okayyyy...antibiotic management xx What are the advantages of Telcoplanin in S.Aureus infections?

Answer 26

Single daily dosing

Question 27

Okayyyy...antibiotic management xx What are the advantages of Linezolid in S.Aureus infections?

Answer 27

Good penetration into bone Very good oral bioavailability

Question 28

Okayyyy...antibiotic management xx What are the advantages of Daptomycin in S.Aureus infections?

Answer 28

Well tolerated Once daily dosing

Question 29

First thing to do when choosing which antibiotics to use if determining if the S.Aureus is methicillin resistant (MSSA/MRSA). What is the first line treatment for a MSSA S.Aureus infection?

Answer 29

Flucloxacillin

Question 30

First thing to do when choosing which antibiotics to use if determining if the S.Aureus is methicillin resistant (MSSA/MRSA). What is the first line treatment for a MRSA S.Aureus infection?

Answer 30

Any other antibiotic previously mentioned e.g. Vancomycin, Telcoplanin, Linezolid, Daptomycin

Question 31

For S.Aureus bacteremia, what is the treatment duration?

Answer 31

14 days, IV antibiotics

Question 32

If patient has a penicillin allergy, flucloxacillin cannot be used. What is the alternative?

Answer 32

Vancomycin

Question 33

Why is Daptomycin not suitable for lung infections?

Answer 33

It is inactivated by pulmonary surfactant in the lungs