Skin and Soft Tissue Infections Flashcards
Differentiate between impetigo and ecthyma
Impetigo is a superficial infection of skin characterized by pustules / vesicles progressing to crusting
Ecthyma is a deeper variant of vesicles/pustules that evolve into punched out ulcer
Define what is erysipelas
Erysipelas is a more superficial infection of skin involving lymphatics and are characterized by tender, erythematous plaque with well-demarcated borders
Define a furuncle and carbuncle
Furuncle is an infection of the hair follicle with small subcutaneous abscess
Carbuncles a collection of furuncles
What are some of the host defense mechanisms? Therefore, describe the pathogenesis of SSTI.
Host defense mechanism
1. Skin act as physical, chemical and immunological barrier.
2. Continuous renewal of epidermal layer –> shedding of keratocytes and skin microbiota
3. Sebaceous secretion: inhibit growth of bacteria and fungi
4. Normal commensal skin microbiome: prevent colonization and overgrowth of pathogenic strains
Disruption of normal host defenses leads to an overgrowth and invasion of skin and soft tissues by pathogenic microorganisms.
List some of the risk factors associated with SSTI
Disruption of skin barrier
- Traumatic: lacerations, recent surgery, burns, abrasions, crush injuries
- Non traumatic: ulcer, tinea pedis, toe web intertigo, chemical irritants
- Impaired venous and lymphatic drainage: sapheous vasectomy, obesity, chronic venous insufficiency
Conditions predisposing infections: DM, Cirrhosis, Neutropenia, HIV, Immunosuppressive and transplantation
History of cellulitis
What is some advice you can counsel a patient should they have any of the risk factors, to prevent SSTI?
Manage current predisposing risk factors (e.g. treat tinea pedis)
Prevent dry and cracked skin
Good foot care for DM patients to prevent wound and ulcers
Good wound care to maintain skin integrity by treating acute traumatic wounds
What is some advice you can counsel a patient should they have any of the risk factors, to prevent SSTI?
Manage current predisposing risk factors (e.g. treat tinea pedis)
Prevent dry and cracked skin
Good foot care for DM patients to prevent wound and ulcers
Good wound care to maintain skin integrity by treating acute traumatic wounds
Using the systematic approach, how do I confirm the presence of an SSTI infection?
Acknowledge the risk factors through history taking and checking for underlying disease; recent trauma, bites, burns and water exposure; animal exposure; travel history.
Diagnose with swab culture and blood culture
When is a blood culture indicated?
Severe cases with marked systemic signs of infection
Immunocompromised patients
Is swab cultures always necessary?
No. Mild superficial infections do not need a swab culture.
How should a swab culture be collected?
Deep in wound after surface is cleansed
Base of closed abscess
Curettage
What is a telltale sign that differentiates between an impetigo and ecthyma?
Impetigo have dried discharge forming honey crust on erythematous base and are well localised lesions
Ecthyma are lesions extending through epidermis and deep into dermis. A significant sign would be pruritus
What is the differences between erysipelas and cellulitis?
Erysipelas usually located in lower extremities of the upper dermis. They are painful plaques raised above skin and have well-demarcated edges
Cellulitis usually found in lower extremities and are non-elevated, acute and diffuse, can spread thus have poor demarcation. They are unilateral as well
Identify the type of pathogen associated with impetigo
Staphylococci
Streptococci
Identify the type of pathogen associated with ecthyma
Group A streptococcus
What are some nonpurulent SSTI?
Cellulitis
Erysipelas
