What is Gas Gangrene?
Gas gangrene, also known as myonecrosis, is a deadly infection that affects deep soft tissues. It’s caused by bacteria known as Clostridium, with the most common kind being Clostridium perfringens. These bacteria were commonly found in war wounds, but thanks to advances in wound care, cleanliness, and antibiotics, this incidence has drastically decreased since the Vietnam War era, from 5% to just 0.1%. The bacteria can also enter the body through puncture wounds or during surgical procedures, especially ones in the digestive system such as bile duct or intestinal surgeries, due to accidental contamination of the surgical wound with gut bacteria.
What Causes Gas Gangrene?
Clostridial infections are a type of bacterial infection that commonly occur in tissue that has been injured, but they can also happen out of the blue. These infections usually affect deeper tissues like muscles and can quickly spread, potentially causing a severe body-wide infection commonly known as sepsis.
The infection could show up hours or even weeks after the initial injury and the intrusion of the bacteria. However, not everyone exposed to these bacteria will develop a serious condition known as gas gangrene. Different factors, including the body’s overall health and certain characteristics of the bacteria, determine whether the infection gets worse or not.
People with weaker immune systems or those with reduced oxygen supply to their tissues (possibly due to an injury or poor blood flow) are more likely to get these infections. The most common bacteria that cause these infections include Clostridium perfringens, Clostridium septicum, and Clostridium histolyticum. Clostridium septicum is often responsible for gas gangrene that appears spontaneously and is associated with digestive system issues, like colon cancer. On the other hand, Clostridium perfringens and Clostridium histolyticum are often tied to infections after an injury.
More recently, there have been reports of an uncommon pathogen, Clostridium sordellii, causing fatal shock syndrome and uterine gas gangrene after medical abortion with oral mifepristone and vaginal misoprostol. The incidents of Clostridium sordellii are also increasing with the use of black tar heroin injections, commonly referred to as “popping.” This bacterium has been found to cause deep tissue infections associated with childbirth and infections after gynecologic procedures, including septic abortions, which can also lead to gas gangrene of the uterus.
Risk Factors and Frequency for Gas Gangrene
In the United States, there are about 1000 cases of myonecrosis each year. However, in less developed countries where healthcare and antibiotics are not as accessible, it’s likely the numbers are even higher, but the exact amount is unknown.
Even with great care, like early detection, surgery, antibiotic treatment, and oxygen therapy, the overall chance of death is still 20% to 30%. Some studies have even found it can be as low as 5% to 10%. If the disease isn’t treated, though, it’s fatal 100% of the time.
People with certain conditions can have a higher chance of dying from myonecrosis. These include people with a weakened immune system, diabetes and spontaneous infections. Their mortality rate can be as high as 67% or more. If the infection includes the soft tissue of the abdomen or chest wall, the mortality rate can shoot up to 60%. In contrast, infections in the limbs have a mortality rate that ranges from 5% to 30%.
Signs and Symptoms of Gas Gangrene
Gas gangrene, or myonecrosis, is a severe infection that often shows signs like fever, chills, and pain. Interestingly, the skin inflammation might appear less serious than the deep-seated infection beneath might suggest. If left untreated, the condition can quickly worsen, leading to sepsis (a dangerous response to an infection) and potentially even death. One noticeable characteristic of gas gangrene is a wound discharge that looks like dishwater and has a musty smell.
This infection can affect the blood vessels that nourish larger areas of tissue, causing the skin’s fatty layer down to the fascia (a band or sheet of connective tissue) and deeper muscles to die off. If the infection involves the nerves, the pain may not be as intense as the extent of the infection might suggest.
When gas gangrene becomes severe, it can lead to potentially life-threatening conditions. These include septic shock (a sudden drop in blood pressure), adult respiratory distress syndrome (a severe lung condition), disseminated intravascular coagulation (a condition that causes clots and bleeding), and hemolysis (breakdown of red blood cells), which can cause a type of anemia called hemolytic anemia.
Any patient with a skin infection (cellulitis) that starts to show additional worrying signs – such as a crackling sensation when the skin is touched due to gas in the tissue, or skin that looks blackish or dusky – should be checked for possible gas gangrene.
Testing for Gas Gangrene
If your doctor suspects that you may have gas gangrene, there are a few immediate steps they will likely take to confirm the diagnosis. These include a comprehensive set of blood tests and other lab work, such as a complete blood count (CBC), comprehensive metabolic panel (CMP), urine analysis, and tests for blood clotting (PT and APTT). They may also take blood and tissue samples from the wound to be grown in a lab (cultures) to identify what type of bacteria is causing the infection.
Additional blood tests that can help detect a severe body-wide infection known as sepsis, which often occurs alongside gas gangrene, include arterial blood gas (ABG), lactic acid, and pre-calcitonin tests.
Images of the infected body part collected through methods like X-rays, computed tomography (CT scan), and ultrasound can also be very helpful. These pictures allow your doctor to see how extensive the infection is, whether there’s an abscess, and if gas is present in the tissues.
However, all these tests and screenings should not delay the most urgent treatment for gas gangrene – surgical removal of dead tissue (surgical debridement). During surgery, your doctor may take a tissue sample from deep within the wound for further testing, which helps identify the exact type of bacteria involved. This information then guides the choice of antibiotics to treat the infection.
Treatment Options for Gas Gangrene
When dealing with rapidly advancing infections, it’s crucial to start treatment promptly with a combination of antibiotics, surgery to remove infected tissue, fluids given through a vein (intravenous or IV), close monitoring in an intensive care unit, and special oxygen therapy. This situation is considered a surgical emergency, so a surgeon’s advice should be sought as soon as possible.
There should be no delay in starting antibiotic treatment even before lab results come back, as waiting could further put the patient’s health at risk. Common antibiotics used in this setting include vancomycin, tazobactam, or a kind called “carbapenem,” or a combination of another antibiotic called “ceftriaxone” with metronidazole. If the doctor thinks the disease causing the infection could be gas gangrene or an aggressive skin infection, they might add penicillin and clindamycin to the treatment plan. Clindamycin can help lower the amount of toxins produced by certain bacteria and lessen the impact of these toxins on the body. Clindamycin is not a standalone treatment, however, so it should be used in combination with another antimicrobial drug like penicillin.
A type of surgical procedure, known as a fasciotomy, might be needed to alleviate pressure that builds up in tissue compartments as the infection progresses into deeper tissue. The surgical focus is on removing all the dead tissue and any foreign matter such as soil, debris, or shrapnel. It’s also crucial to wash the wounds with a lot of sterile saltwater solution.
Hyperbaric oxygen therapy is an additional treatment that can enhance survival rates when combined with antibiotics and surgical debridement (cleansing and removal of dead or infected tissue). In this therapy, patients are placed in a special pressurized chamber where they breathe in pure oxygen, which can help slow down the production of bacterial toxins, improve the effectiveness of antibiotics, treat inadequate blood supply to the tissue, reduce swelling, and speed up the healing process. It is important that care is coordinated by a team of specialists including an intensivist, surgeon, orthopedic surgeon, urologist, gynecologist, infectious disease specialist, hematologist/oncologist, gastroenterologist, and a doctor who specializes in hyperbaric oxygen therapy.
Early IV antibiotics and surgical debridement, followed by hyperbaric oxygen therapy, greatly improve the survival rates of patients with an otherwise critical disease. While the fatality rate can be around 30% with just intravenous antibiotics and surgical removal of dead tissue, the addition of hyperbaric oxygen therapy can reduce the fatality rate further to between 5 and 10%.
Hyperbaric oxygen therapy can be delivered in single patient chambers or multiple patient chambers. The choice of type of chamber has implications for patient care management during treatment and also for ease of patient access by healthcare providers.
In treating gas gangrene, hyperbaric oxygen therapy treatments start twice a day, reducing to once daily treatments once the patient’s condition has stabilized. Continued therapy can speed up healing, prepare the tissue for grafting (transplanting healthy tissue to help close wounds), and help manage large defects left after surgical debridement of dead tissue. Keep in mind that this therapy isn’t without risks; these can include oxygen toxicity (too much oxygen in body tissues), low blood sugar (mainly in insulin-dependent diabetics), and barotrauma or damage to body tissues caused by changes in pressure.
At a later stage of treatment, doctors may consider using negative pressure wound dressing therapy. This involves applying a vacuum to the wound to promote healing once the removal of dead tissue through surgical debridement is complete.
What else can Gas Gangrene be?
There are several medical conditions that might be considered during a diagnosis, including:
- Abdominal abscess (a collection of pus in the abdomen)
- Abdominal trauma (an injury to the abdomen)
- Bacteria sepsis (a life-threatening response to infection)
- Elective abortion (a planned termination of pregnancy)
- Emphysematous cholecystitis (a severe gallbladder infection)
- Group A streptococcal infections (infections caused by group A streptococcus bacteria)
- Septic shock (a severe infection that affects the whole body)
- Toxic shock syndrome (a rare, life-threatening complication of certain types of bacterial infections)
- Vibrio infection (an infection, usually caused by eating undercooked seafood)
Recovery from Gas Gangrene
If you have gas gangrene, the daily or frequent removal of damaged tissue, known as surgical debridement, is needed until the damaging infection is under control. You would also receive hyperbaric oxygen therapy (a treatment in which you breathe pure oxygen in a pressurized room or tube) twice a day until the tissue death stops and tissue recovery signs, such as the formation of new connective tissue called granulation tissue, become evident.
Additionally, you would require constant intensive care. If the kidneys fail, a process called hemodialysis (which removes waste and excess fluid from the blood when the kidneys aren’t functioning correctly) may be needed. In severe cases, extracorporeal membrane oxygenation (ECMO) may be required, which is a treatment that uses a pump to circulate blood through an artificial lung and send it back into the body, particularly for patients suffering from a severe lung condition called adult respiratory distress syndrome (ARDS).
Once the infection clears up, you may still require additional wound treatments, potentially including negative pressure wound therapy (a therapeutic technique using a vacuum dressing to enhance and promote wound healing), advanced tissue regeneration techniques, and reconstructive surgeries such as skin grafting and flap procedures to close the surgical wounds. Many people with gas gangrene need lengthy stays in intensive care units (ICU), followed by extensive rehabilitation to recover and regain their physical abilities. This might mean moving to a long-term care facility for recurrent wound care, possibly hyperbaric oxygen therapy, and therapeutic rehabilitation programs that include physical therapy and occupational therapy.