Necrotizing myositis, also known as spontaneous gangrenous myositis is relatively rare. It is a necrotizing infection of skeletal muscle caused by group A Streptococcus or other beta-hemolytic streptococci. It may be preceded with skin abrasions or blunt trauma. The infection will progress over several hours and involve muscle groups and soft tissue. If the patient develops streptococcal toxic shock syndrome, then they have an onset of hypotension. These patients will not have evidence of gas formation in tissue on physical or radiographic examination.
Necrotizing fasciitis in an infection of the deeper tissues that results in progressive destruction of the muscle fascia and overlying subcutaneous fat. Infection is usually spread along the muscle fascia due to it’s relatively poor blood supply. The process progresses rapidly over several days, from erythematous area to change in skin color from red-purple to patches of blue-gray. Within three-five days onset, skin breakdown with bullae will occur and frank cutaneous gangrene can be seen. By this time, the involved area is no longer tender but has become anesthetic secondary to thrombosis of small blood vessels and destruction of superficial nerves in the subcutaneous tissue. There are two types of necrotizing fasciitis.
Type I of necrotizing fasciitis is a mixed infection caused by aerobic and anaerobic bacteria. Risk factors include diabetes, PVD, immune compromised, and recent surgery. Type II necrotizing fasciitis is generally monomicrobial. It is caused by group A Streptococcus or other beta-hemolytic streptococci that is either alone or in combination with other pathogens, most commonly S. aureus. Patient’s culture came back with growth of Staphlococcus aureus.
(Stevens, 2016)
The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System, WIfI, is a system for classifying the severity of limb threat that is intended to reflect clinical considerations that impact management and amputation risk. WIfI is an acronym for wound, ischemia, and foot infection. Each category has a different grade.
For wound, a grade 0 is rest pain; no wound; no ulcer; no gangrene. Grade 1 is a small shallow ulcer(s) on distal leg or foot, any exposed bone is only limited to distal phalanx(ie. Minor tissue loss, limb salvageable with possible simple digital amputation or skin coverage). Grade 2 involves a deeper ulcer on dis