What is gangrene? I know it's an infection; how fast can it spread?

Dear Reader,  

Gangrene is a potentially fatal condition involving the death of body tissue, caused by an infection or loss of blood flow. Blood transports oxygen, antibodies, and nutrients to tissues, which are necessary for survival. This essential function can be compromised when an injury causes substantial loss of blood, or an open wound allows bacteria to enter and leads to infection (more on this in a bit). While gangrene is uncommon, certain health conditions that impair the ability to fend off infection or restrict blood circulation can put people at higher risk. You asked how fast gangrene can spread — unfortunately, it can spread very quickly. Some bacteria can infect a seemingly minor cut or scrape and spread rapidly to large areas within a day or two. Luckily, these quick moving infections are rare, and the best way to keep them at bay is to reach out to your health care provider if you notice any symptoms. Keep reading for more information about how to spot gangrene and steps to prevent it.   

Gangrene often occurs in the body’s extremities (such as toes and fingers), but it can affect any tissue, including muscles and organs. One cause of gangrene may be bacteria (including StreptococcusStaphylococcus aureus, and most often Clostridium) entering the body through open wounds and spreading under the skin to neighboring areas or through the bloodstream to the entire body. Some bacteria create toxins that flow into the body, destroying tissues and causing severe illness. Another cause of gangrene is when the blood supply to a particular part of the body is cut off (known as ischemia) and isn’t getting any oxygen. When the body's tissues go without oxygen for too long or if an infection begins, the tissue or infected organs can die (known as necrosis). The causes and symptoms of gangrene vary slightly depending on the sub-type:  

  • Dry gangrene: results from loss of blood to the tissues, leading to dry, shriveled, black or purplish-blue skin   
  • Wet gangrene: a fast-spreading and potentially deadly type caused by bacterial infection that leads to swelling, fluid, and a putrid smell  
  • Gas gangrene: is associated with Clostridium perfringens bacterial infection; impacts deep muscle tissue, and leads to pale, gray, or purplish-red skin that looks bubbly (appearing as gas under the skin)  
  • Internal gangrene: occurs in internal organs such as intestines or gallbladder that can lead to a bulge, such as a hernia  
  • Fournier’s gangrene: presents in the genital organs after an infection in the genital area or urinary tract   
  • Meleney’s gangrene: causes painful skin lesions and typically occurs as a complication of surgery   

List adapted from Mayo Clinic.  

It’s worth mentioning that gangrene is both potentially fatal and rare, but certain medical conditions that weaken the immune system or impact blood circulation, such as diabetes, blood vessel diseases (atherosclerosis, peripheral artery disease, Raynaud’s disease), HIV, obesity, and severe wounds including burns, frostbite, and crush injuries increase the risk. Other factors that may increase the chances of gangrene include intravenous drug use, smoking, or complications from surgery. If you suspect you might have gangrene, it’s best to seek treatment as soon as possible to reduce the spread of the infection. If someone has gangrene, they may notice some severe symptoms in the affected area that warrant medical attention, including:  

  • Redness and swelling: an area of redness and swelling around a wound that grows rapidly larger  
  • Coldness, pain, or numbness: pain may be sudden and severe and then develop into numbness (once the tissues have died)  
  • Changes in skin texture: thin, shiny, tight, or flaking skin over the affected area  
  • Fluid or blood-filled blisters: Frothy or clear fluid leaking from the area. This may also include a crackly, puffy sensation of gas gathering underneath the infected skin  
  • Changes in skin color: depending on the type of gangrene, the skin could be blue, purple, bronze, red, or black. The skin may progress to a deep black when the tissues are completely dead and are decomposing.  
  • Bad-smelling discharge: a foul or rotten smell leaking from a sore or from the wound  
  • Symptoms of septic shock (a potentially fatal condition): if the infection has spread throughout a person’s body, they may have fever and chills, nausea and vomiting, severe weakness, dizziness, rapid heart rate, and confusion  

List adapted from Mayo Clinic and Hopkins Medicine 

Chances of surviving gangrene are higher when detected early. Treatment often includes an operation to remove the dead tissue, which can help prevent the infection from spreading and help restore blood flow. The affected area may be treated through debridement, where an area of tissue is removed, or amputation, where an arm, leg, hand, foot, finger, or toe is completely removed. Other treatments include intravenous antibiotics, hyperbaric oxygen therapy (in which very high pressures of pure oxygen are used to treat the gangrenous area), and blood thinners to make sure that blood clots don't form. 

All this said, gangrene is rare and there are measures you can take to prevent it. To reduce the chances of developing an infection, whenever you have a cut or scrape, it’s best to clean it carefully with mild soap and water and use any antibiotic ointment your health care provider recommends. If you've recently had surgery, it’s best to follow instructions about how to care for and bandage any incisions. And any time you notice an injury or surgical wound that seems to be getting redder, more swollen, or more painful rather than improving, get medical care immediately. 

Last updated Aug 27, 2021
Originally published May 17, 2002

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