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Public Health - Seattle & King County

Group A Strep Necrotizing fasciitis (NF)

What is it?
  • Necrotizing fasciitis (NF) is a severe, uncommon infection that damages muscle, fat, and skin.
  • NF is caused by many types of bacteria, but group A streptococci (strep) are the most common cause and are sometimes referred to as "flesh-eating" bacteria in the press.
  • Bacteria that can cause NF can get into the body through a break in the skin or other injury. The infection spreads along the lining (called fascia) under the skin that includes the fat that surrounds muscles and internal organs.
  • People with medical conditions that weaken their defenses against infections are at increased risk, including cancer, diabetes mellitus, kidney dialysis, alcohol abuse, chronic heart and lung disease, skin wounds, and weakened immune systems from medical conditions or immune suppressing drugs. People who inject illicit (street) drugs are also at increased risk for NF.
  • Less often, healthy people can get NF, but in some cases no cause can be found.
  • Fever
  • Moderate to severe pain or tenderness, especially with no apparent injury or wound
  • Swelling
  • Red or dusky blue rash, especially if spreading quickly after the swelling starts
  • Flu-like symptoms such as diarrhea, nausea, fever, confusion, dizziness, and weakness

See a health care provider right away if these symptoms develop.

How is it spread?
  • Group A strep are often found in the throat and on the skin of healthy people. Most group A strep infections cause no symptoms or mild illnesses such as "strep throat," or impetigo
  • On rare occasions, group A strep and other common bacteria can cause severe and even life-threatening diseases such as NF.
  • Although group A strep can spread from person to person, it is rare for even close contacts of people with NF to develop the disease.
Diagnosis and treatment
  • Diagnosis can be difficult, especially early in the infection, and requires surgery in a hospital to examine the deep tissues.
  • Blood tests and CT or MR scans can help make the diagnosis, but sometimes surgery is the only way to be sure.
  • Surgery and intravenous antibiotic treatment are very important as early as possible to treat the infection.
  • See a healthcare provider to check for strep if you have a sore throat with fever.
  • People with strep throat should stay home and away from others until they have completed the first 24 hours of antibiotic treatment.
  • Use good hand washing when someone has strep throat or other strep infection.
  • Thoroughly clean skin injuries, even minor cuts and scrapes, with soap and water and keep the wound clean.
  • If you have new or increasing redness, swelling, wound drainage or pain, see a health care provider right away to check for infection.
For persons in contact with someone who has NF
  • It is not necessary for most persons exposed to someone with NF to receive testing or antibiotic therapy to prevent infection.
  • In some cases, health care providers may recommend antibiotic therapy for close or household contacts of persons with NF (for example, if someone at increased risk for NF lives in the home).
  • All people who have had close contact with someone with NF should watch their health for 30 days and contact their health car provider right away if they develop sore throat, fever, muscle pain, or other symptoms of NF described above.
Report all King County cases to Public Health by calling 206-296-4774.