Erysipelas, Cellulitis, Pyomyositis, Necrotizing Fasciitis and Gas Gangrene
DNB Orthopaedics • October 2024 • Paper I • 10 Marks
Introduction
Soft-tissue infections form a spectrum from relatively superficial infections such as erysipelas and cellulitis to rapidly progressive, life-threatening infections such as necrotizing fasciitis and clostridial myonecrosis.
Their distinction is based primarily on the anatomical layer involved, causative organisms, rate of progression, presence of tissue necrosis and need for surgical intervention.
Anatomical progression
Erysipelas → superficial dermis/lymphatics
Cellulitis → deeper dermis + subcutaneous tissue
Necrotizing fasciitis → fascia + subcutaneous tissue
Pyomyositis → skeletal muscle
Gas gangrene → rapidly destructive muscle infection / myonecrosis
High-Yield Comparison
| Condition | Main Tissue Involved | Classical Organism | Key Clinical Clue | Key Treatment |
|---|---|---|---|---|
| Erysipelas | Upper dermis + superficial lymphatics | Group A Streptococcus | Raised, sharply demarcated erythematous plaque | Antibiotics |
| Cellulitis | Deep dermis + subcutaneous tissue | Streptococci / S. aureus | Diffuse, poorly demarcated erythema | Antibiotics ± drainage if abscess |
| Pyomyositis | Skeletal muscle | S. aureus | Fever + focal painful muscle swelling / abscess | Antibiotics + drainage |
| Necrotizing fasciitis | Superficial fascia + subcutaneous tissue | Polymicrobial or Group A Streptococcus | Pain out of proportion + rapid progression | Immediate radical debridement + IV antibiotics |
| Gas gangrene | Skeletal muscle | Clostridium perfringens | Severe… |