How Do You Get Necrotizing Fasciitis?

What Exactly Happens Inside the Body When Bacteria Enter?

Once bacteria get past the skin barrier, they start multiplying in the deep tissue. The fascia is a poor blood supply area, so the body’s immune cells have a hard time reaching the infection. The bacteria release toxins that destroy tissue and block blood vessels. Without blood flow, the tissue dies. This is why the infection can spread inches per hour in some cases.

The most common bacteria involved include Group A Streptococcus, but others like Staphylococcus aureus and certain anaerobes can also cause it. Research published in the journal Clinical Infectious Diseases found that about 70 percent of cases involve more than one type of bacteria. These bacteria work together to break down tissue faster.

What makes necrotizing fasciitis different from a regular skin infection is the speed. A normal cellulitis infection stays in the skin. Necrotizing fasciitis goes deep into the fascia. The skin on top may look normal at first while the tissue underneath is already dying. This is why early diagnosis is difficult and dangerous.

How Do You Get Necrotizing Fasciitis From Everyday Activities?

Most cases start from something ordinary. A paper cut, a scraped knee, a cat scratch, or even a small burn. The CDC reports that about 25 percent of cases have no obvious entry point at all. This means the bacteria may have entered through a micro-tear in the skin that was too small to notice.

Certain situations raise the risk. People who work with raw fish or shellfish have a higher chance of infection from Vibrio vulnificus bacteria. This is sometimes called “flesh-eating bacteria” in news headlines, though that term is misleading. The bacteria itself does not eat flesh. It releases toxins that kill tissue.

Other everyday exposures include contaminated water. If you have an open wound and go into a hot tub, lake, or ocean, bacteria can enter. The CDC specifically warns against swimming in natural bodies of water with open cuts. Even a small blister from new shoes can be enough.

What Does Research Show About Who Is Most at Risk?

Research shows that certain health conditions make infection more likely. People with diabetes account for roughly 30 percent of all cases, according to data from the National Institutes of Health. High blood sugar weakens the immune system and reduces blood flow to the skin, making it harder to fight off bacteria.

Other conditions that increase risk include:

• Chronic kidney disease
• Liver disease, especially from alcohol use
• Peripheral artery disease
• Obesity with a BMI over 30
• Immunosuppressive medications like steroids or chemotherapy
• HIV or AIDS

Age also matters. People over 60 have a higher risk because the immune system naturally weakens. Studies have found that men are slightly more affected than women, though researchers are not sure why. Some evidence suggests it may be related to higher rates of trauma or skin injuries in men.

How Do You Get Necrotizing Fasciitis After Surgery or Medical Procedures?

Surgical wounds are a common entry point. Any incision breaks the skin barrier. If bacteria from the skin, the environment, or the surgical team enter the wound, infection can start. The overall risk is low, around 0.4 percent of all surgeries, according to the American College of Surgeons. But certain procedures carry higher risk.

Abdominal surgeries, especially those involving the colon, have higher infection rates because bacteria from the gut can contaminate the wound. C-sections also carry risk. A study in Obstetrics & Gynecology found that necrotizing fasciitis after C-section occurs in about 1 in 10,000 cases. While rare, it is serious.

Medical injections like insulin shots or joint injections can also introduce bacteria if the skin is not properly cleaned. IV drug use is another major risk factor. People who inject drugs often reuse needles and do not clean the injection site, which can push bacteria directly into deep tissue.

What Are the First Signs That Infection Is Not Just a Normal Wound?

The earliest symptom is pain that seems out of proportion to the injury. A small cut should not feel like deep burning or stabbing pain. The pain may spread beyond the wound area. Some people describe it as feeling like something is tearing inside.

Other early signs include:

• Swelling that spreads quickly
• Red or purple skin that looks bruised
• Skin that feels warm or hot to the touch
• A fever over 100.4°F
• Nausea or vomiting

As the infection progresses, the skin may blister, turn black, or develop a foul smell. This is a medical emergency. The CDC states that the mortality rate is about 25 percent. That number drops significantly with early treatment. Every hour of delay raises the risk of amputation or death.

Common Misconceptions About How the Infection Spreads

A common myth is that necrotizing fasciitis is contagious. It is not. You cannot catch it from being near someone who has it. The bacteria that cause it are common on skin and in the environment. The infection only happens when those bacteria get into deep tissue through a wound.

Another myth is that only dirty people get it. This is false. The bacteria are everywhere. Good hygiene helps but does not prevent all cases. Even healthy people with clean wounds can develop the infection if the right bacteria enter at the right time.

Some people believe that necrotizing fasciitis always comes from a dramatic injury like a deep knife wound. In reality, most cases come from minor injuries that people ignore. The infection does not discriminate based on how clean or careful someone is. It is about bacteria getting to the wrong place.