SSTIs and Osteomyelitis

Question 1

3 pyodermal infections of the epidermis/dermis?

Answer 1

Impetigo
Erysipelas
Ecthyma

Question 2

What is impetigo usually caused by?

Answer 2

S aureus

Question 3

What is erysipelas usually caused by?

Answer 3

Strep pyogenes

Question 4

What is ecthyma usually caused by?

Answer 4

Strep pyogenes

Question 5

How does erysipelas present?

Answer 5

Infection of the superficial skin (down to dermis) often caused by strep pyogenes, distinct leading edge

Question 6

What is ecthyma?

Answer 6

Deep punched ulcer with yellow crusting affecting epidermis and dermis
Often affects lower legs, shins and dorsum of feet

Question 7

3 infectious conditions affecting hair follicles?

Answer 7

Folliculitis
Furuncle
Carbuncle

Question 8

What are folliculitis, furuncles and carbuncles most often caused by?

Answer 8

S aureus

Question 9

Describe the progression from folliculitis -> furuncle -> carbuncle

Answer 9

Folliculitis = pustule formation around hair follicle, when extends down into root of hair = furuncle
Multiple furuncles = draining abscess formation = carbuncle

Question 10

What is cellulitis?

Answer 10

Tender erythematous skin infection that extends right down to the fascia with no distinct leading edge

Question 11

What is paronychia?

Answer 11

Swollen erythematous lesion surrounding the nail bed usually caused by s aureus or strep pyogenes

Question 12

Pathogenesis of nec fasc?

Answer 12

Painful erythematous infection of skin which crosses fascia of underlying muscles causing compartment syndrome and subsequent muscle necrosis
High fever, sepsis

Question 13

Features of SSTI that might make you think nec fasc rather than cellulitis?

Answer 13

Pain disproportionate to clinical signs
Crepitus - gas gangrene
High fever, sepsis
Bullae or ecchymosis 
Tender beyond visible poorly demarcated borders

Question 14

What is the emergency management of nec fasc?

Answer 14

Radical debridement

Question 15

What bacteria often cause nec fasc?

Answer 15

Mixture of coliforms e.g. E. coli, anaerobes

Can be strep pyogenes

Question 16

What specific blood test can be done to assess extent of nec fasc?

Answer 16

CK (compartment syndrome leading to rhabdomyelysis)

Question 17

Management of non-complicated cellulitis?

Answer 17

Flucloxacillin

Or erythromycin, clarithromycin

Question 18

What treatment is used for cellulitis with sepsis or facial cellulitis?

Answer 18

IV Co-amoxyclav

Question 19

What is Ludwig’s angina?

Answer 19

Nec fasc of submandibular space

Question 20

What is Fournier’s gangrene?

Answer 20

Nec fasc of scrotum or vulva

Question 21

What are the 4 aetiological types of nec fasc?

Answer 21

1 = polymicrobial incl coliforms and anaerobes
2 = GAS/staph
3 = gram negative microbes (vibrio, aeromonas hydrophila)
4 = fungal incl candida

Question 22

Who does type 1 nec fasc (polymicrobial anaerobes and coliforms) most commonly affect?

Answer 22

The immunocompromised / chronically diseased

Question 23

Who can type 2 nec fasc (GAS/s aureus) affect?

Answer 23

Anyone of any health

Question 24

Who does type 3 nec fasc (gram negs e.g. Vibrio spp, aeromonas hydrophila) affect?

Answer 24

Marine association so fisherman, swimmers in seawater etc

HIGHLY VIRULENT

Question 25

What bedside test is used for suspected nec fasc?

Answer 25

Bedside finger test - incise 2cm down to deep fascia under local
Lack of bleeding, malodorous dishwater pus, lack of normal tissue resistance
Culture and gram stain this

Question 26

Antibiotic management of nec fasc?

Answer 26

Start IV broad spectrum abx according to local guidelines, ensuring coverage of GAS/MSSA, anaerobes + coliforms and gram negatives
E.g. Meropenem + clindamycin

Question 27

From superficial to deep, what are the 3 main layers of the skin?

Answer 27

Epidermis
Dermis
Subcutis