Anthrax Treatment Options: Antibiotics, Antitoxins, And Supportive Care

What is anthrax?

Anthrax is a disease caused by the Bacillus anthracis bacteria, it is spread through bacterial spores found in the ground that are normally activated when in contact with bodily fluids. These spores can enter the body through wounds, inhalation or through the gut. When an animal is infected, it can then spread the infection to humans, through infected animal products.¹ 

Symptoms of anthrax vary by infection type but commonly include fever, difficulty breathing, nausea, vomiting, and headache. Without treatment, fatality rates are high, especially for inhalation anthrax, which has an 85% mortality rate. Prompt treatment with antibiotics, antitoxins, and supportive care is critical to stop the disease's rapid progression. Severe cases may require ventilators and intravenous fluids to aid recovery.²

There are different ways in which a person can be infected by anthrax, and these forms of infection also coincide with different symptoms. The different types of anthrax infection are cutaneous (skin contact), gastrointestinal (stomach and intestines), inhalation (lungs), and through injections.

1. Cutaneous anthrax occurs when spores enter through the skin, generally through a wound. It is the most common form of anthrax. The symptoms of cutaneous anthrax are:
   • Raised, itchy bump developing into a sore with a black centre
   • Swelling around the affected area and lymph nodes
   • Possible flu like symptoms³
2. Gastrointestinal anthrax is caused by eating meat from an infected animal, causing symptoms anywhere along the gastrointestinal tract through to the large intestine. The symptoms of this type of anthrax infection include:
   • Nausea and vomiting
   • Abdominal pain
   • Fever
   • Severe bloody diarrhoea (during later stages)
   • Sore throat and/or difficulty swallowing⁴
3. Inhalation anthrax is caused by the inhalation of bacterial spores. This form of anthrax produces more severe symptoms, making it the most fatal form of anthrax infection. The symptoms include:⁵
   • Flu-like symptoms
   • Shortness of breath & difficulty breathing
   • Coughing up blood
   • Fever
   • Shock - involves collapse of the respiratory system
   • Meningitis

When inhaled, anthrax is deadlier because the anthrax spores have greater access to the body's systems through which toxins can be transported (the lymph system).

4. Injection anthrax is the least common form of anthrax infection, and it is mainly caused through the injection of illegal substances, through which bacteria can enter the body. The symptoms of injection anthrax include:
   • Redness around the injection site
   • A large amount of swelling
   • Shock
   • Multiple organ failure
   • Meningitis⁶

The way in which someone is infected with anthrax can change the severity of symptoms, which in turn also increases the chances of the infection being fatal. The cause of infection would also inform the best course of action when treating anthrax. A diagnosis of anthrax would be confirmed with a biopsy of the affected area. In the case of cutaneous or injection anthrax, medical professionals would conduct blood, stool, mucus, or lumbar puncture tests.⁷

Most people are familiar with anthrax because of the 2001 American Anthrax attacks, when letters laced with anthrax were mailed to several government officials, causing 5 deaths and infecting 17 others. Those suspected to have been infected with biological weapons or bio-terrorism-related anthrax require immediate intervention and the most intensive treatments, though no such attacks have taken place since.⁸

Anthrax treatment

Due to the potentially fatal nature of anthrax; and the need for quick medical intervention, anthrax infections require hospitalisation for treatment. The usual treatment involves the administration of antibiotics.²

Antibiotics for treating anthrax

Antibiotics are the first port of call for healthcare professionals when combatting anthrax. These can be administered orally or intravenously. The main antibiotics prescribed are:

• Penicillin
• Amoxicillin
• Doxycycline
• Ciprofloxacin 

Oral antibiotics are suggested in less severe cases; for more severe infections (inhalation or gastrointestinal anthrax), intravenous antibiotics would be used to more aggressively battle the infection. Antibiotics can also be combined if a severe infection requires it. In systemic cases, the course of antibiotics may be up to 14 days.⁹

Treatment may be different if it is suspected that the anthrax infection is related to a biological weapon or bio-terrorism, the course of antibiotics would then be administered for up to 60 days to ensure that the bacteria that causes anthrax is destroyed.

Antitoxins for treating anthrax

Antitoxins focus on neutralizing the toxins released by the Bacillus anthracis bacteria, and they are generally given alongside antibiotics. The two main antitoxins used in anthrax treatment are Raxibacumab and Obiltoxaximab, both of which are monoclonal antibodies.

Raxibacumab targets the protective antigen component of the anthrax toxin, neutralizing its ability to deliver lethal and edema factors into cells. Similarly, Obiltoxaximab binds to protective antigens and prevents its interaction with cell surface receptors, thereby inhibiting toxin entry into cells. These antitoxins are particularly crucial in severe cases such as inhalation anthrax, where toxin levels in the body can rise rapidly. While they do not kill the bacteria, their role in neutralizing toxins makes them a critical adjunct to antibiotic therapy. 

By mitigating toxin effects, antitoxins reduce systemic damage, prevent organ failure, and improve survival outcomes. Administering antitoxins early in the course of infection significantly enhances their effectiveness, as delayed use may allow toxins to irreversibly damage tissues and organs.¹⁰

Supportive care in anthrax treatment

During anthrax treatment, medical professionals would offer supportive care by maintaining proper breathing, keeping fluid levels stable and avoiding shock.

This is done through:

• Mechanical Ventilation - for patients with serious respiratory symptoms, mechanical ventilation is crucial, especially in the inhalation of anthrax. This form of anthrax can cause severe lung damage, leading to fluid buildup and respiratory failure. Ventilators support breathing and maintain oxygen levels, buying time for antibiotics and antitoxins to work effectively
• Hemodynamic Support - Hemodynamic support is essential for stabilizing blood pressure and preventing septic shock caused by anthrax toxins. This is achieved through intravenous fluids to restore blood volume and vasopressors, such as norepinephrine, to tighten blood vessels and raise blood pressure. Continuous monitoring ensures the circulatory system remains stable¹¹

These interventions, combined with antibiotics and antitoxins, form a comprehensive approach to managing severe anthrax, significantly improving survival rates when administered promptly. Early action is critical to prevent irreversible damage.

Summary

In conclusion, anthrax is a potentially fatal disease caused by Bacillus anthracis, requiring prompt treatment to prevent severe complications or death. The bacteria's spores, dormant in the soil, activate upon contact with bodily fluids and can infect humans through various routes: cutaneous (via skin wounds), gastrointestinal (from consuming contaminated animal products), inhalation (spores breathed into the lungs), and injection (from tainted drugs).

Symptoms vary depending on the form of infection but commonly include swelling, fever, flu-like symptoms, shock, and severe complications such as bloody diarrhoea or blood in coughs. Immediate treatment with antibiotics, administered orally or intravenously depending on severity, is crucial to halt bacterial growth and destruction. Antitoxins may also be employed to neutralize the toxins released by the bacteria, preventing symptom progression.

For severe cases, advanced interventions like mechanical ventilation, hemodynamic support, and vasopressors are often required to stabilize the patient and prevent shock, particularly in inhalation anthrax. Early and effective medical intervention is key to managing anthrax infections and reducing fatality risks.