Caused by streptococcal or mixed bacterial infections a soft tissue infection that causes necrosis of fascia and subcutaneous tissue
Invasive GAS disease is a severe infection, bacteria have invaded parts of the body, such as the blood, deep muscle and fat tissue or the lungs.
Dental infections are the most common etiology, followed by trauma, peritonsillar and pharyngeal abscesses, and osteoradionecrosis
The bacteriology consists of anaerobes, gram negative rods, group A b-hemolytic strep, and staph species.
The onset of symptoms is usually 2 to 4 days after the insult.
The skin is smooth, tense and shiny with no sharp demarcation, and develops a dusky discoloration with poorly defined borders.
There is localized necrosis of skin which is secondary to thrombosis of nutrient vessels as they pass through the zone of involved fascia.
If untreated, this will progress to frank cutaneous gangrene. Clinically there is sudden pain and swelling and the skin becomes warm,
erythematous, and edematous and can be mistaken for cellulitis or erysipelas.
Fasciitis necrotizing
Three zones of skin are recognized and include a wide peripheral zone of erythema surrounding a tender dusky zone, and a central zone of necrosis that eventually ulcerates.
There can be anesthesia of the skin from involvement of the cutaneous nerves as they pass through necrotic subcutaneous tissue.
These patients often have a low-grade fever and can be anemic and jaundiced from bacterial hemolysis. Massive amounts of fluid can be sequestered with resultant hyponatremia, hypoproteinemia, and dehydration.
Hypocalcemia can develop from necrosis of subcutaneous fat and subsequent saponification.