SSTI

Question 1

Factors that impair skin barrier function

Answer 1

Humidity & Moisture
- Age(extreme ends; young and old)
- Infection
- Physical damage - pressure, friction, lacerations
- Physical environment - contact with urine, faeces, sweat & chronic wound fluid
- Ischemia - lack of perfusion
- Diseases - DM
- Drugs - immunosuppressants, SGLT2i
- pH
- Excessive soap and detergent use

Question 2

Pathophysiology of SSTIs

Answer 2

Disruption of normal host defenses –> overgrowth and invasion of the skin and soft tissues by pathogenic micro-organisms

Question 3

What are the protective mechanisms of the skin?

Answer 3

• Continuous renewal of epidermal layer results in shedding of keratocytes and skin microbiota
• Sebaceous secretions inhibits growth of many bacteria and fungi
• Normal commensal skin microbiome prevents colonization and overgrowth of more pathogenic strains

Question 4

Risk factors of SSTI

Answer 4

• Disruption of skin barrier
  - Traumatic(Lacerations, recent surgery, burns, abrasions, crush injuries, open fractures, injection drug use, human and animal bites, insect bites)
  - Non-traumatic(Ulcers, tinea pedis, dermatitis, toe web intertrigo, chemical irritants)
  - Impaired venous & lymphatic drainage(Saphenous vanectomy, obesity, chronic venous insufficiency)
  - Peripheral artery disease
• Conditions that predispose to infection
  - (DM, Cirrhosis, Neutropenia, HIV, Transplantation & immunosuppressive medications)
• History of cellulitis

Question 5

Prevention of SSTI

Answer 5

• Good care to maintain skin integrity
• Acute traumatic wounds should be copiously irrigated, foreign objects removed, devitalized tissues debrided

Question 6

How do you diagnosis SSTI?

Answer 6

clinical judgement based on history taking and physical examination
- underlying diesease, recent trauma, bite, water exposure, animal exposure, travel history
* Culture may not be required for mild and superficial wounds
* if want culture from pus/exudates/tissues, collected from
1) deep in the wound after surface is cleansed
2) base of a closed abscess where bacteria grow
3) by curettage, NOT wound swab/irrigation
* Blood culture - ONLY for severe cases with systematic symptoms/ immunocompromised patients