SSTI

Question 1

Skin’s protecting factors

Answer 1

1. Dry surface
2. Fatty acids
3. Acidic pH 5.6
4. Renewal of epidermis
5. Low temperature

Question 2

Which age group is impetigo most common in?

Answer 2

Children, on face or extremities

Question 3

Toxin-producing strains

Answer 3

Staphylococcus aureus

Question 4

Causative organisms of impetigo and ecthyma

Answer 4

Staphylococcus aureus, B-hemolytic Streptococci eg. S.pyogenes

Question 5

Predisposing factors

Answer 5

1. Poor hygiene
2. Sharing of personal items
3. Excessive moisture
4. DM
5. High bacterial innocula
6. Reduced blood supply

Question 6

Is it reasonable to treat impetigo and ecthyma without culture?

Answer 6

YES, empirically cover for S. aureus and B-hemolytic Streptococci

Question 7

What are some specific risk factors of purulent SSTIs?

Answer 7

1. Sharing of personal items
2. Poor hygiene
3. Close physical contact
4. Crowded living quarters

Question 8

Causative organism of purulent SSTIs

Answer 8

Staphylococcus aureus, single most common organism, tend to be a/w purulent infection
- Large skin abscesses may be polymicrobial

Question 9

Does empiric selection of abx have to cover CA-MRSA?

Answer 9

No, still low prevelance <30-35% in SG compared to western countries
-usually susceptible to oral non beta-lactams eg clindamycin

Question 10

Mainstay of purulent SSTIs treatment

Answer 10

I&D

Question 11

When will adjunctive abx be required for purulent SSTIs?

Answer 11

1. Unable to drain completely
2. Lack of response to I&D
3. Extensive disease involving several sites
4. Extremes of age
5. Immunosuppressed eg chemotherapy, transplant
6. SIRS

Question 12

Are cultures recco for cellulitis and erysipelas?

Answer 12

not commonly recco

- consider (if possible): purulent infections after I&D, immunosuppressed eg chemo/transplant, SIRS criteria

Question 13

Cellulitis from Bite Wounds

Answer 13

Staphylococcus aureus, Streptococcus spp
Specific organisms:
- Pasteurella multocida (animal bites)
- Eikenella corrodens (human bites)
- oral anaerobes eg Prevotella spp, Peptostreptococcus spp

Question 14

Induration

Answer 14

localised hardening of soft tissue of the body

Question 15

Does DFI require culture?

Answer 15

Mild: optional

Moderate-severe: deep tissue culture after cleansing wound area and before starting abx (if possible), avoid skin swabs

Question 16

Pseudomonal risk factors

Answer 16

Warm climate, frequent exposure to water

Question 17

When must we empirically cover Pseudomonas aeruginosa?

Answer 17

1. severe infection

2. failure of abx not active against P.aeruginosa

Question 18

Causative organisms of DFI

Answer 18

typically polymicrobial, staph and strep most common

• Gram neg bacilli eg E.coli, Klebsiella, Proteus (Pseudo less common), chronic wounds or previously treated with abx
• Anaerobes eg. Peptostreptococcus, Veillonella, Bacteriodes, ischaemic or necrotic wounds

Question 19

Signs and smx of inflammation

Answer 19

Erythema, warmth, pain, tenderness, induration