What is Anthrax?

From the Guidelines

Anthrax should be treated with antibiotics such as ciprofloxacin or doxycycline for 60 days, and in severe cases, combination antibiotic therapy is recommended, with the addition of antitoxin products such as raxibacumab or obiltoxaximab for postexposure prophylaxis and treatment. Anthrax is a serious bacterial infection caused by Bacillus anthracis, which primarily affects livestock but can infect humans through contact with infected animals or their products [ 1 ]. The disease presents in three main forms: cutaneous (skin lesions), inhalational (respiratory symptoms), and gastrointestinal (digestive symptoms) [ 1 ].

Key Considerations

• The incubation period for anthrax is usually <2 weeks, but can be prolonged for months in the case of inhalational anthrax [ 1 ].
• Prompt treatment is essential as inhalational anthrax can be fatal if not treated early [ 1 ].
• The bacterium forms spores that can remain dormant in soil for decades, making it difficult to eradicate completely from the environment [ 1 ].
• Prevention includes avoiding contact with infected animals or their products and proper handling of potentially contaminated materials [ 1 ].

Treatment Options

• Antibiotics such as ciprofloxacin (500 mg orally twice daily) or doxycycline (100 mg orally twice daily) for 60 days [ 1 ].
• Combination antibiotic therapy for severe cases, often including a fluoroquinolone plus one or two additional antibiotics [ 1 ].
• Antitoxin products such as raxibacumab or obiltoxaximab for postexposure prophylaxis and treatment [ 1 ].

High-Risk Individuals

• Laboratory workers, military personnel, and those who handle animal products from high-risk areas are at increased risk of anthrax infection and may require vaccination [ 1 ].

From the Research

Anthrax Overview

• Anthrax is a zoonotic disease that can occur in three forms: cutaneous, gastrointestinal, and inhalation, depending on the mode of infection 2.
• The inhalation form of anthrax can be used as a biological warfare agent, prompting the introduction of specific guidelines by the USA Centers for Disease Control and Prevention 2.

Treatment and Prophylaxis

• Postexposure prophylaxis is indicated to prevent inhalational anthrax, and therapy with ciprofloxacin or doxycycline is recommended for adults and children for 60 days 2.
• However, studies suggest that shorter prophylaxis durations, such as 35 days of ciprofloxacin administration, may be effective in clearing the spore burden in 95% of patients 3.
• Combination treatment using purified antibodies and antibiotics, such as ciprofloxacin, has shown to be more effective than antibiotic treatment alone in a rodent anthrax model 4.
• Other agents with in vitro activity against Bacillus anthracis include rifampicin, vancomycin, imipenem, chloramphenicol, penicillin, and ampicillin, clindamycin, and clarithromycin 2.

Antibiotic Susceptibility

• All isolates of Bacillus anthracis tested were susceptible to ciprofloxacin and doxycycline 5.
• Penicillin and amoxicillin, with or without clavulanate, showed in vitro activity against all B. anthracis isolates, while ceftriaxone demonstrated lower-level in vitro activity 5.

Vaccination and Protection

• Postexposure vaccination has been shown to enhance the protection afforded by antibiotic prophylaxis alone and completely protect animals against inhalational anthrax 6.
• A short course of antibiotic prophylaxis combined with vaccination has been shown to protect non-human primates from a high-dose spore challenge 6.