Did you know certain bacteria can consume the skin, fat, and the tissue surrounding the muscles?
Necrotizing fasciitis, caused by group A Streptococcus (GAS), is a "flesh-eating" bacteria that interferes with blood flow, invades the tissue, and results in tissue necrosis. Chronic disease conditions can lead to severe necrosis of subcutaneous muscle tissue and inflammation of the fascia of a muscle or organ. Long-term effects include multiple organ failure, toxic shock, and disseminated intravascular coagulation.
What types of bacteria are responsible for this disease?
Streptococcus species causing infections are Staphylococcus aureus, Streptococcus pyogenes, Clostridium perfringens, or Aeromonas hydrophila.
Which individuals are more prone to necrotizing fasciitis?
People suffering from diabetes, heart disease, peripheral vascular disease, and cancer, taking immunosuppressive medications due to a weakened immune system, are prone to pathogenic bacterial infections and necrotizing fasciitis, leading to inflammation.
How is it transmitted?
Bacteria belonging to Streptococcus sp. are commonly found in the water ecosystem and form the microfauna of the skin (Figure 1). These flesh-eating bacteria can enter through a tiny cut in the skin and induce tissue necrosis and inflammation. Poisons produced by bacteria spread to various human organs and result in sepsis. Furthermore, to prevent the spread of bacteria, the victim has to get the affected parts of the body amputated.
What are the genetics of this disease?
First, horizontal gene transfer moves foreign DNA into the initially harmless cell of Streptococcus. Bacteriophages, viruses that specifically attack bacteria, frequently deliver this DNA. Taking foreign genes is advantageous for the bacteria as it increases the likelihood of its survival. A second horizontal gene transfer increases the pathogenicity of the bacteria.
Figure 1: Adverse effects of Necrotizing fasciitis: A flesh-eating bacteria
Which nation is most affected by this disease?
Several studies that have documented the prevalence of necrotizing fasciitis are available:
South Korea has an incidence of 0.86 cases per 100,000 population; New Zealand sees an incidence of 1.3 cases per 100,000 population, whereas the United States has 4 to 10.3 cases per 100,000 population. Thus, the United States is the most affected nation.
What are the symptoms observed in this disease?
Consult a doctor immediately if your skin turns red, starts swelling quickly, and you get a fever. Other symptoms include ulcers, blisters, or black spots on the skin, pus oozing out from infected areas, dizziness, diarrhoea, and nausea.
How can you prevent this disease, and what is its possible treatment?
These bacteria are insensitive to penicillin as they produce beta-lactamase, which hydrolyses the beta-lactam ring in penicillin, making this antibiotic inactive. The drug of choice is vancomycin as it binds to the acyl-D-ala-D-ala portion of the bacterial cell wall, preventing cell wall formation and killing the bacteria. Wound cleansers that are approved by the FDA can be used for chronic non-healing wounds and diabetic foot ulcers, as well as for post-surgical and burn wounds. Antibiotics like ampicillin or ampicillin-sulbactam coupled with metronidazole or clindamycin are administered right away as part of the treatment. Surgical debridement can also help.
Why is it important to focus on this disease at present?
On October 19, 2022, authorities in one of the Florida counties still recovering from a Category 5 Atlantic hurricane issued a warning that a potentially fatal microbe, popularly known as flesh-eating bacteria, had killed four people on Friday and infected 29 more, bringing the state's death toll to 11. Supercharged hurricanes are currently breeding along the US Atlantic coast. During flooding, the bacteria Vibrio vulnificus, which frequently dwells in warm, brackish waters, often spreads faster. Based on this background, it is important to be aware of the prognosis, symptoms, and treatment options of the disease as it is actively spreading to other nations as well.
How is it ideal to learn as part of the biotechnology syllabus?
The study of necrotizing fasciitis can give us exposure to many fields of biotechnology like:
i) Microbiology
Group A Streptococci are prevalent on the skin and in the throat, they cause Necrotizing fasciitis. They are round-to-ovoid cocci with a mucosal or smooth morphology. The field of microbiology will help distinguish between different strains of bacteria.
ii) Diagnostics
It is an important field as it helps in the identification of different diseases. Currently, magnetic resonance imaging (MRI) is the gold standard for the diagnosis of Necrotizing fasciitis. It can also be detected by the Finger Test. For the finger test, local anaesthesia is given to the suspected involvement area. To reach the deep fascia, a 2-cm incision must be made in the skin. An indication of necrotizing fasciitis is the absence of bleeding.
iii) Disease Biology
The study of the disease helps us to understand the prognosis, etiology, pathogenesis, and manifestation of the disease. Morbidity, co-morbidity, and mortality rates will help us understand the severity of the disease, and the general population will need to be made aware of this.
iv) Drug discovery
The study of the disease is necessary to formulate the drug against it. This drug will also help in treating other bacterial infections caused by Streptococcus.
v) Immunology
Immunology is an important field as this disease will help us understand how our body’s defense mechanism fights against it. If it is weak (in the case of immunocompromised individuals), special technology and engineering of immune cells can help.
Authors:
Ms. Khushi Kiran, Dr. Manjusha Dake
Dr. D. Y. Patil Biotechnology and Bioinformatics Institute,
Dr. D. Y. Patil Vidyapeeth (Deemed to be University),
Tathawade, Pune - 411033, Maharashtra, India.