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necrotizing fasciitis

Tuesday 17 June 2003

Necrotizing fasciitis (NF) , commonly known as flesh-eating disease or flesh-eating bacteria, is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue.

Type I describes a polymicrobial infection, whereas Type II describes a monomicrobial infection.

Many types of bacteria can cause necrotizing fasciitis:

- group A streptococcus (Streptococcus pyogenes)
- Staphylococcus aureus
- Vibrio vulnificus
- Clostridium perfringens
- Bacteroides fragilis

Historically, Group A streptococcus made up most cases of Type II infections.

However, since at least 2001, another serious form of monomicrobial necrotizing fasciitis has been observed with increasing frequency. In these cases, the bacterium causing it is methicillin resistant Staphylococcus aureus (MRSA), a strain of S. aureus which is resistant to methicillin, the antibiotic used in the laboratory that determines the bacterium’s sensitivity to flucloxacillin or nafcillin that would be used for treatment clinically.รง

Bacterias do not actually eat the tissue. They cause the destruction of skin and muscle by releasing toxins (virulence factors), which include streptococcal pyogenic exotoxins. S. pyogenes produces an exotoxin known as a superantigen. This toxin is capable of activating T-cells non-specifically, which causes the overproduction of cytokines.

Etiology:

- streptococci
- staphylococci

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