What Is Necrotizing Fasciitis

Picture this: you’re putting your feet up on the couch after a long day weeding your flower beds. You see a small graze on your calf and think nothing of it. The next day, you’re limping and can barely stand on two feet, let alone think about touching that tiny cut you once shrugged off. In most circumstances, you may be justified in resting your leg and thinking it will get better.  However, this could just be the beginning stages of the life-threatening ordeal that is necrotizing fasciitis. Read on to learn more about this grave, flesh-eating infection and, in particular, just how easy it is for a simple scrape to escalate to a trip to intensive care. 

Overview

Necrotizing fasciitis, as the name suggests, involves the inflammation and eventual death of the fascia, a layer of tissue deep beneath your skin that can be likened to something out of a horror film. The fascia acts to provide structure by surrounding a number of your muscles and organs, and due to containing lots of nerve endings, any damage to this area can be incredibly painful.^1,2 Necrotizing Fasciitis is a disease that may rapidly ‘snowball’ from a simple scratch, cut or break in the skin into a condition that is life-altering and potentially fatal.^1,2,3,4 Although necrotizing fasciitis is incredibly rare, it is crucial to be aware of this ‘flesh-eating’ disease’s symptoms, as they may one day help preserve your life and limb. 

Necrotizing fasciitis most commonly affects areas surrounding the tummy (abdomen) as well as extremities such as the legs.^2,3 Although this condition initially causes damage to the fascia, as time progresses, the disease can quickly spread to surrounding areas such as the muscle and subcutaneous tissue.^1,2,3,4 If left untreated, bacteria and their associated toxins are free to enter the bloodstream, almost certainly leading to widespread organ dysfunction, sepsis or toxic shock syndrome.^2,3 It is at this point that the necrotizing fasciitis becomes fatal.^2,3

Causes of necrotizing fasciitis

Cases of necrotizing fasciitis may be due to a singular causative species of bacteria termed ‘monomicrobial’, or they may be the result of numerous different strains of bacteria in the case of ‘polymicrobial’ necrotizing fasciitis.^1,2,3 Commonly associated bacteria include Staphylococcus aureus, group A Streptococci, and a number of other anaerobic species.^1,2,3,4 The specific bacteria involved will depend on the site of infection, and the species isolated will often be different between monomicrobial and polymicrobial cases.^1,2,3 Infiltration of these bacteria into the fascia via an opening, such as a wound, allows for them to cause damage to these tissues by the production of toxins, causing inflammation, damage and reduced blood supply.^1,2,3 Due to poor blood flow to the fascia, the cells begin to die and break down.^1,2,3

As humans, we will frequently come into contact with the above bacteria, as they are often present abundantly throughout your body (i.e. your skin, urinary tract, or gastrointestinal tract).² It is unclear why this condition may occur when we are in contact with such offending microorganisms almost every day.² However, the risk factors detailed below may play a significant role in the progression of disease.  

Risk factors

Risk factors for necrotizing fasciitis include:

• Problems with blood supply, such as peripheral vascular disease^2,3,4
• Diabetes^2,3,4
• Excessive alcohol intake (i.e. alcoholism)² 
• A weakened immune system (Immunosuppression) or cancer^2,3,4
• Kidney disease^3,4
• Illicit drug use³
• Following an operation¹

Signs and symptoms of necrotizing fasciitis

• Severe pain^1,2,3,4
• Redness of area or changes to surrounding skin^1,2,3,4
• Swollen area around cut^1,2,3,4
• Weeping wound or pus^1,2,3,4
• Extreme tiredness^1,2,3,4
• ‘Flu-like’ aches^1,2,3,4
• Fever^1,2,3,4

Diagnosis

Necrotizing fasciitis overlaps considerably with several other infections, and as a result, it may be difficult to distinguish necrotizing fasciitis from these in the first instance.^2,3,4 Diagnosis may involve many different assessments, including:

• Physical observation of the wound or affected area to check for redness, swelling, or visible changes to your skin.^1,2,3,4 However, some of these physical changes may not be obvious during the early stages of infection.^2,3 Purple patches or blisters are a sign that may be seen in later stages of the disease.² 
• A CT scan of the affected area may allow your doctor to visualise the layers of the fascia and see if there is any build-up of fluid, gas or any signs suggestive of inflammation caused by infection.^2,3,5
• Assessment of pain related to a visible wound.^1,2,3,4 Necrotizing fasciitis often presents with severe pain, which is often described as disproportionate to the appearance of the affected area.^(1,2,3,4) Severe pain is a significant symptom seen in necrotizing fasciitis and should ring alarm bells to those involved in its diagnosis.^1,2,3,4
• Wound swabs if there is any pus or discharge around the affected area - these can be used to culture bacteria to observe what bacteria has grown.^1,2,3
• Clinical observations for blood pressure, temperature, respiratory rate, and heart rate can all be used to indicate the presence of a widespread or systemic infection, as is often the case in necrotizing fasciitis.³
• Blood tests may be used as potential indicators of necrotizing fasciitis.^1,5,6 Blood tests may be used to identify the presence of infection by measuring the levels of C-reactive protein (CRP), white blood cells (WBC), neutrophils, serum lactate, creatine kinase (CK) or metabolic changes observed in the blood, which may all be used to support the presence of a potentially severe infection.^1,5,6 The extent to which these are present or raised acts as a strong indicator of disease, and the LRINEC scoring tool is often used to support a diagnosis of necrotizing fasciitis.^1,3,5,6

A prospective diagnosis of necrotizing fasciitis often relies on the assessment of the above factors and your medical team’s suspicion of disease. However, as a diagnosis of necrotizing fasciitis can only confidently be confirmed at the point of surgery (physically exploring the affected area), suspected cases of necrotizing fasciitis will be acted upon rapidly until excluded.^1,3,5,6

Management and treatment for necrotizing fasciitis

Care of people with necrotizing fasciitis involves numerous strategies which, when used together, aim to minimise the risks of lasting illness. People with necrotizing fasciitis have the potential to be medically unstable and in need of intensive, closely monitored treatment to ensure the best chances of survival.^1,3,5 As a result, it may be in your best interests to be cared for in an intensive care unit.^2,3,5

Due to the potentially widespread nature of necrotizing fasciitis, supportive treatment will parallel that of sepsis and will likely include intravenous fluid replacement, as well as medications to maintain effective blood flow to your organs.^1,3,5 The widespread symptoms associated with severe infection in the late stages of necrotizing fasciitis may mean that you require extra support to maintain the effective function of your kidneys and your cardiovascular system.^1,2,3,5

Antibiotics – As with most infections, antibiotics play a vital role in killing the bacteria responsible. Choices of antibiotics should be in line with local guidelines; however, they will likely involve a broad-spectrum medication in combination with an antibiotic targeting anaerobic (grow without the presence of oxygen) microbes in the early stages (i.e. penicillin combined with clindamycin).^1,2,3,5 These antibiotics will prove effective against many different bacteria, and until your medical team can identify the specific organism(s) responsible, it will provide the best option for treatment initially.^1,2,3,5 However, following the identification of the implicated causative microorganism will allow for your treatment to be tailored based on bacterial resistance patterns and sensitivities.^1,2,3,5

One major difficulty in treating necrotizing fasciitis, specifically concerning antibiotic therapy, results from the damage of blood vessels supplying the fascia associated. This damage of networks supplying blood to the infected tissue means that penetrating the infected areas with antibiotics becomes very troublesome, and for that reason, treatment by surgical means will be crucial in your care.^1,2,3,5 

Surgery – In necrotizing fasciitis, time is very much against you. To prevent further spread of infection and prevent catastrophic deterioration, swift surgical intervention will be critical. This treatment involves a team of surgeons tasked with the identification and removal of infected or dead tissue to prevent the progression of disease.^1,2,3,5,7 This technique is termed ‘debridement’, and unfortunately, the removal of significant amounts of tissue may be essential to preserve life.⁷

Surgery will typically take place across several sessions as it may prove difficult to remove all of the infected tissue in one sitting.⁷ Therefore, careful observation combined with repeated interventions to debride any infected/dead tissue will prove essential in offering you the best chance of recovery when combined with the effective use of antibiotics and supportive treatments.^3,7

Other options for the treatment of those with necrotizing fasciitis may include the use of intravenous immunoglobulin therapy in specific cases (help to support recovery from widespread infection) as well as hyperbaric oxygen therapy (improved wound healing processes).^3,7,8 These options for treatment are used as an adjunct to the above strategies, and their use would be substantially weighed up by your medical team due to controversies surrounding how effective they are.^3,7,8,9

Complications

As touched on above, the major complication associated with necrotizing fasciitis is a severe systemic infection, which could further result in toxic shock syndrome or sepsis.^1,2,3,4,5,10 This condition may be linked to a significant number of medical implications, such as problems with bleeding or blood clotting, cardiovascular collapse, and organ failure, ultimately leading to death.^1,2,3,4,5,10

As well as this, due to the potential for damage to the fascia and the need for surgical intervention of the affected area, there may be lasting effects on the surrounding tissue, such as nerve damage, pain, altered sensation as well as the potential implications of significant surgical intervention, i.e. those requiring skin grafts or limb amputation.^1,3,7,11 Both of these may be linked to postoperative complications such as infection, graft failure and changes to the function of the affected limb or area.¹¹  

Summary

Necrotizing fasciitis is a condition that can very rapidly escalate from a seemingly minor cut to a life-threatening situation. Due to its diagnosis being challenging and relying heavily upon your medical teams’ suspicions, it is crucial that you seek medical attention as early as possible. If left untreated, the complications and general course of the disease are very often fatal, and failing that, the interventions required to preserve life may have a profound impact on your well-being and day-to-day functioning for years to come. So don’t ignore that small graze, that insect bite or that painful nick in your skin; please ensure you seek timely advice from an appropriate medical professional.