Skin Infections

Question

| Criteria        | Cellulitis           | Erysipelas  | Erysipeloid  |
| ------------- |-------------| -----| -----|
| Causative Organism | Usually Staphylococcus aureus or Streptococcus species | Streptococcus pyogenes | Erysipelothrix rhusiopathiae |
| Skin Appearance | Red, swollen, warm, and tender with poorly defined borders | Bright red, well-demarcated, raised, and shiny with distinct borders | Reddish-brown, well-defined, and indurated with raised borders |
| Lymphatic Involvement | May or may not involve lymphatic vessels | Frequently involves lymphatic vessels, causing lymphangitis | Rarely involves lymphatic vessels |
| Common Sites | Lower extremities, especially the legs | Face, particularly cheeks and nose | Hands, fingers, or other areas in contact with fish or meat |
| Risk Factors | Skin trauma, underlying skin conditions, immunosuppression | Impaired lymphatic drainage, chronic venous insufficiency, diabetes mellitus | Occupational exposure to fish or meat |
| Treatment | Empirical antibiotics targeting Staphylococcus aureus and Streptococcus species | Penicillin or cephalosporins targeting Streptococcus pyogenes | Penicillin or erythromycin targeting Erysipelothrix rhusiopathiae |

Clinical significance:
- Cellulitis is a common skin infection that can occur in any age group and is often caused by bacteria entering through a break in the skin. It requires prompt treatment with antibiotics to prevent complications.
- Erysipelas is a superficial skin infection that affects mainly the face and is caused by Streptococcus pyogenes. It is characterized by well-demarcated, raised, and shiny skin lesions. Prompt treatment with antibiotics is necessary to prevent spread and complications.
- Erysipeloid is a rare infection caused by Erysipelothrix rhusiopathiae, commonly found in fish and meat. It typically affects individuals with occupational exposure. Prompt treatment with antibiotics is necessary to prevent complications and to alleviate symptoms.

Aspect	Necrotizing Fasciitis	Myonecrosis (Gas Gangrene)
Definition	A severe bacterial infection that affects the fascia, subcutaneous tissue, and can progress to involve muscle and other structures.	A bacterial infection characterized by rapid destruction of muscle tissue, caused by Clostridium species, most commonly Clostridium perfringens.
Pathogenesis	Usually caused by group A Streptococcus or Staphylococcus aureus. Bacteria enter the body through a break in the skin and rapidly spread along the fascial planes.	Caused by Clostridium species, which produce toxins that destroy muscle tissue. These bacteria can enter the body through wounds contaminated with soil or feces.
Clinical Features	- Severe pain and tenderness at the site of infection

Criteria	Cellulitis	Erysipelas	Erysipeloid
Causative Organism	Usually Staphylococcus aureus or Streptococcus species	Streptococcus pyogenes	Erysipelothrix rhusiopathiae
Skin Appearance	Red, swollen, warm, and tender with poorly defined borders	Bright red, well-demarcated, raised, and shiny with distinct borders	Reddish-brown, well-defined, and indurated with raised borders
Lymphatic Involvement	May or may not involve lymphatic vessels	Frequently involves lymphatic vessels, causing lymphangitis	Rarely involves lymphatic vessels
Common Sites	Lower extremities, especially the legs	Face, particularly cheeks and nose	Hands, fingers, or other areas in contact with fish or meat
Risk Factors	Skin trauma, underlying skin conditions, immunosuppression	Impaired lymphatic drainage, chronic venous insufficiency, diabetes mellitus	Occupational exposure to fish or meat
Treatment	Empirical antibiotics targeting Staphylococcus aureus and Streptococcus species	Penicillin or cephalosporins targeting Streptococcus pyogenes	Penicillin or erythromycin targeting Erysipelothrix rhusiopathiae