Factors that impair skin barrier function
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
Pathophysiology of SSTIs
Disruption of normal host defenses –> overgrowth and invasion of the skin and soft tissues by pathogenic micro-organisms
What are the protective mechanisms of the skin?
- 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
Risk factors of SSTI
- 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
Prevention of SSTI
- Good care to maintain skin integrity
- Acute traumatic wounds should be copiously irrigated, foreign objects removed, devitalized tissues debrided
How do you diagnosis SSTI?
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
