Both necrotizing fasciitis and gas gangrene are diseases characterized by rapid, spreading tissue necrosis. Compare and contrast the infectious agents, the pathology and treatment

Question

What will be an ideal response?

Answer 1

Both diseases are caused by bacterial pathogens that are introduced under the surface of the epidermis by injuries. The pathogens produce a variety of toxins responsible for the necrosis and the rapid spread of the infection. Treatment is surgical removal of the infected necrotic tissue followed by an antibiotic cocktail delivered IV.

Necrotizing fasciitis is primarily caused by the Gram-positive cocci Streptococcus pyogenes and Staphylococcus aureus, which are capable of infecting living subcutaneous tissue when injury provides access. Both are aerobic bacteria commonly present in and on the surface of the body, and both produce a variety of anti-phagocytic factors that interfere with a major line of defense. In addition, these organisms produce several toxins and exoenzymes that damage tissue, leading to cell death. The infection is initially difficult to detect beneath relatively intact skin. When S. aureus is the infecting agent, treatment may be difficult due to antibiotic resistance.

Gas gangrene is the result of infection with the strictly anaerobic, endospores-forming Gram-positive bacillus Clostridium perfringens. Disease results when endospores are introduced into a wound, and the injury results in tissue necrosis. The endospores can germinate in the oxygen-depleted environment of the necrotic tissue, and the vegetative cells produce a variety of toxins which cause further cell death. The bacteria grow rapidly, and their metabolic activities result in the production of gasses which accumulate in the necrotic tissue. The injury and necrosis are evident early in the course of infection. Treatment includes antitoxins and pressurized oxygen therapy in addition to the surgery and antibiotics.
Bloom's Taxonomy: Analysis
Section: Bacterial Diseases of the Skin and Wounds
Learning Outcome: 19.11, 19.23