dermatologic disorders
Necrotizing Soft Tissue Infection
Etiology of Necrotizing Soft Tissue Infection
There are two subtypes of necrotizing soft-tissue infection (NSTI): Type I Type II species). These organisms typically extend to subcutaneous tissue from a contiguous ulcer or infection, or after trauma. Streptococci can arrive from a remote site of infection via the bloodstream. Perineal involvement (also called Fournier gangrene) is usually a complication of recent surgery, perirectal abscess, periurethral gland infection, or retroperitoneal infection resulting from perforated abdominal viscera. Patients with diabetes are at particular risk of type I NSTI. Type I infections often produce gas in the soft tissue, making its manifestation similar to that of gas gangrene ( Clostridial Soft-Tissue Infections ), which is a monomicrobial infection ( This photo shows life-threatening infection of the subcutaneous fat and muscles by streptococci (group A), causing widespread necrosis involving the lower back. © Springer Science+Business Media This photo shows a patient who has a necrotizing subcutaneous infection with discoloration and swelling of the scrotum. LIVING ART ENTERPRISES, LLC/SCIENCE PHOTO LIBRARY This photo shows Fournier gangrene, which is necrotizing fasciitis of the perineum. Image courtesy of Noel Armenakas, MD. The 1st photo on the left shows a preoperative image of the dorsal right arm with hemorrhagic bullae and cyanotic skin lesions. The 2nd photo from the left shows erupted vesicles on the medial arm. The 3rd and 4th photos show postoperative changes with extensive skin necrosis on the dorsal side and myonecrosis and cyanotic changes of underlying flexor muscles on the medial aspect. © Springer Science+Business Media Type II NSTIis monomicrobial and is most commonly caused by group A beta-hemolytic streptococci;Staphylococcus aureusis the second most common pathogen. Patients tend to be younger with few documented health problems but may have a history of IV illicit drug use, trauma, or recent surgery. The infection has the potential for rapid local spread and systemic complications such as toxic shock. A subgroup of type II NSTI usually occurs with aquatic injuries sustained in warmer coastal areas.Vibrio vulnificusis the usual pathogen. Clostridial Soft-Tissue Infections (gas gangrene) may develop spontaneously or after a deep, traumatic injury. Similar to type I NSTI, gas often develops in the tissue; however, as in type II NSTI, clostridial myonecrosis is typically a monomicrobial infection. 1.Stevens DL, Bryant AE: Necrotizing soft-tissue infections.N Engl J Med377(23):2253–2265, 2017. doi: 10.1056/NEJMra1600673 