Necrotizing infections of the skin are severe forms of cellulitis that are characterized by death of infected tissue (necrosis). Necrotizing skin infections that spread on the outer layers of the skin are called necrotizing cellulitis. Other necrotizing soft tissue infections spread deep in the skin along the surface of the muscle (fascia) and are called necrotizing fasciitis.
Symptoms of necrotizing soft tissue infection can include the following:
- The infected skin is red and is warm when you touch it.
- Sometimes the infected skin can be swollen.
- Gas bubbles may form under the skin.
- The person often runs a high fever and feels quite sick.
- Treatment involves removing dead skin, sometimes requiring extensive surgery, and intravenous antibiotics treatment.
Symptoms often begin just as cellulitis. The skin may look pale at first, but quickly becomes red or bronze. It can be warm to the touch and sometimes swollen. Later, the skin turns violet and often develops large fluid-filled blisters (bullae). The fluid is brown, watery, and sometimes foul-smelling. Areas of dead skin also turn black (gangrene).
Some types of infections produce gas, including those caused by Clostridia and mixed bacteria. The gas creates bubbles under the skin or in the blisters themselves, causing the skin to feel crackly when pressed. Initially the infected area is painful; however, as the skin dies, the nerves stop working, and the area loses sensation.
The person usually feels very ill and experiences high fever, rapid heart rate, and mental deterioration ranging from confusion to unconsciousness. Blood pressure may fall because of toxins secreted by the bacteria and the body's response to the infection.
A doctor makes a diagnosis of necrotizing soft tissue infection based on its appearance, particularly the presence of gas bubbles under the skin. X-rays may show gas under the skin as well. The specific bacteria involved are identified by laboratory analysis of the infected fluid and tissue samples. However, treatment must begin before a doctor can be certain which bacteria are causing the necrotizing infections.
Bacterial Infection - Occasionally, bacterial infection can cause small blood vessels to clot in the infected area. The clotting causes the tissue fed by these vessels to die because they aren't receiving blood. Since the body's immune defenses (white blood cells and antibodies) travel through the bloodstream, clotting prevents them from reaching the infected area. As a result, the infection spreads rapidly and may be difficult to control. Death can occur, even with appropriate treatment.
Puncture Wounds & Lacerations - Some necrotizing soft tissue infections begin at puncture wounds or lacerations, especially in wounds contaminated with dirt and debris.
Surgical Incisions - Necrotizing infections can begin in surgical incisions or even healthy skin.
Side-Effect of Other Diseases - Sometimes the conditions of diverticulitis, intestinal perforation, or tumors of the intestine can lead to the development of necrotizing infections of the abdominal wall, genital area or thighs. These infections occur when certain bacteria escape from the intestine and spread to the skin.
Please note that the majority of soft-tissue infections do not lead to the death of skin or adjacent tissue.