IC14 SSTI

Question 1

How should cultures be taken from wound?

Answer 1

Should be deep in wound after surface is cleansed
Base of closed abscess
By curettage

Question 2

Difference between Impetigo and Ecthyma (type of lesion, how deep)

Answer 2

Impetigo is clear vesicles, reach epidemis
Ecthyma is ulcer, reach dermis

Question 3

Risk factors for MRSA (7 points)

Answer 3

Antibiotic use
Recent hospitalisation or surgery
Prolonged hospitalisation
Intensive care
Hemodialysis
MRSA colonisation
Proximity to MRSA colonised or infected patients

Question 4

Likely pathogen for Impetigo or Ecthyma

Hence what is the treatment for limited / multiple lesions?

Culture directed?

How many days of therapy?

Answer 4

MSSA, Grp A-D strep

Limited: No treatment needed, self limiting

Multiple lesions:
Empiric therapy
PO Cephalexin or Cloxacillin

Penicillin allergy
Mild allergy
Cefuroxime (replace Cephalexin)

Severe allergy
PO Clindamycin

Culture directed (Strep A, Pyogenes)
Penicillin V
Amoxicillin

Culture directed (MSSA)
PO Cephalexin or Cloxacillin

5-7 days

Question 5

What is the mainstay of treatment for purulent SSTI? (Furuncles, Carbuncles, Skin abscesses, Purulent cellulitis)

Answer 5

Incision and Drainage

Question 6

When to use systemic antibiotics in purulent SSTI? (7 points)

Answer 6

Unable to drain completely
No response to I&D
Extensive disease involving several sites
Very young or very old
Immunocompromised
Signs of systemic illness (SIRS criteria)
Severe disease

Question 7

Common pathogens for purulent SSTI (Furuncles, Carbuncles, Skin abscesses, Purulent cellulitis)

Answer 7

MSSA
Strep (grp A-C,G)
Some gram (-)
anaerobes

Question 8

What is the treatment for mild, moderate, severe purulent SSTI, assuming no coverage for (-) and anaerobes

Treatment duration?

Answer 8

Mild infection
I&D + Warm compress to promote drainage

Moderate infection + Systemic symptoms
I&D + Oral antibiotics
Cloxacillin
Cephalexin
Penicillin allergy: Clindamycin

Severe infection
I&D + IV antibiotics
IV Cloxacillin
IV Cefazolin
Clindamycin (for allergy)
Vancomycin (for MRSA)

5-10 days

Question 9

What if need empiric MRSA coverage for purulent SSTI? (oral and IV options) (3 points each)

Answer 9

Oral
Co-trimoxazole (but does not cover Grp A-D strep)
Doxycycline
Clindamycin

IV
Vancomycin
Daptomycin
Linezolid

Question 10

Empiric gram (-), anaerobic coverage for purulent SSTI?

Answer 10

Amox-Clav

Question 11

What are examples of non purulent STI? (2 points)

Common pathogen?

Answer 11

Cellulitis, Erysipelas

Grp A beta hemolytic strep (Strep Pyogenes)

Question 12

How to differentiate mild, moderate and severe non purulent SSTI (Cellulitis or Erysipelas)

Answer 12

Mild: no systemic signs of infection

Moderate: signs of infection, some purulence

Severe: systemic signs of infection, failed oral therapy or immunocompromised + consider possibility of necrotising infections → Broad coverage: gram (+), (-), anaerobes

Question 13

Coverage for mild VS moderate nonpurulent SSTI?

Hence what is the treatment?

Answer 13

Mild: Grp A strep
Cover: Use oral antibiotic
Penicillin V
Cephalexin
Amoxicillin
Allergy: Clindamycin

Moderate: May use IV
similar to moderate purulent SSTI
Cover: Grp A strep + MSSA
Cefazolin
Cloxacillin
(penicillin allergy) Clindamycin

If water exposure
Add Ciprofloxacin
Cover Aeromonas, Vibrio and Pseudomonas

Question 14

What to cover for nonpurulent SSTI?

Treatment for severe nonpurulent SSTI

Answer 14

Pseudomonas, Grp A strep

IV antibiotics (cover Pseudomonas, water exposure)
Pip-Tazo
Meropenem
Cefepime

MRSA risk factor
Add IV Vancomycin, Daptomycin, Linezolid

Question 15

How long should symptoms take to improve in general for SSTI

Answer 15

2-3 days

Question 16

Why should we not use mupirocin for mild cases?

Answer 16

Mild cases are self limiting

Mupirocin only used for MRSA decolonisation

Question 17

How does DFI occur?

Answer 17

1) Peripheral neuropathy
Decreased pain sensation

2) Vasculopathy
Worsened by hyperglycemia and hyperlipidemia

3) Immunopathy
Impaired immune response
Worsened by hyperglycemia

1-3 causes ulcer formation, wounds → Bacterial colonisation, penetration and proliferation → DFIs

Question 18

How to tell if an wound is infected?

Answer 18

Purulent + 2 signs (Redness, Tenderness, Warmth, Pain, Induration- skin thicker due to inflammation)

Question 19

Are cultures needed for mild, moderate, severe DFI?

Answer 19

Mild dont need

Question 20

Criteria for Mild DFI

Cover which bugs?

Drug of choice

Answer 20

< 2cm erythema around ulcer
Cover (+) only (Grp A-D strep + MSSA)

Use oral drugs for Mild DFI
Use Cephalexin, Cloxacillin, Clindamycin
MRSA: Clindamycin, Doxycycline
(cotrimox has poor beta hemolytic coverage)

Question 21

Moderate DFI requirement?

Need cover what?

Hence treatment?

Answer 21

> 2cm erythema around ulcer
(+), (-), Anaerobes

Use IV for Moderate DFI
Cefazolin + Metronidazole
Ceftriaxone + Metronidazole
Amox-Clav
MRSA: IV Vanco, Dapto, Linezolid

Question 22

Requirement for Severe DFI

Need cover what?

Hence treatment?

Answer 22

> 2cm erythema around ulcer
Signs of systemic infection

(+), (-), Anaerobes, Pseudomonas

Treatment
Pip-Tazo

Meropenem

Cefepime + Metronidazole
Metronidazole → Anaerobes

Ciprofloxacin + Clindamycin
Ciprofloxacin → (-), Pseudomonas
Clindamycin → (+), anaerobes

Add IV MRSA if have risk factors

Question 23

Duration of therapy for DFI if no bone involvement (mild, moderate, severe)

Answer 23

Mild: Up to 2 weeks
Moderate: Up to 3 weeks
Severe: up to 4 weeks

Question 24

Duration of therapy if have bone involvement?

Amputation VS Residual infected soft tissue VS Residual viable bone VS No surgery

Answer 24

Amputation: Up to 5 days
Residual infected soft tissue: Up to 3 weeks
Residual viable bone: 4-6 weeks
NO surgery: > 3 months

Question 25

Adjunctive measures for wound care (5 points)

Answer 25

Debridement

Off-loading
Reduce weight put on leg

Apply dressing to control excess exudation

Foot care
Daily inspection
Prevent wound and ulcers

Optimal glycemic control