Sandbox JA

Medical Therapy

The treatment of anthrax infection includes antimicrobial and antitoxin agents. This treatment and postexposure prophylaxis differs from other bacterial infections because:

• Production of toxin
• Potential antibiotic resistance
• Frequent occurrence of meningitis
• Presence of latent spores must be taken into account when selecting postexposure prophylaxis or a combination of antibiotics for treatment of anthrax.

Hospitalized patients for systemic anthrax should be immediately treated with a combination of broad-spectrum intravenous antimicrobial drug treatment pending confirmatory test results because any delay may prove fatal.

Because meningitis and hemorrhagic brain parenchymal infection was observed in ≤50% of cases, meningitis must be considered in all cases of systemic anthrax. Therefore antibiotics to treat possible meningitis must have good penetration of the central nervous system (CNS).

Because of the presence of a spore form of Bacillus anthracis, antibiotic therapy should be continued for 60 days to clear germinating organisms

Antimicrobial Treatment

Follow-up Oral Treatment for Systemic Disease

Once patients with systemic illness who were exposed to aerosolized spores have completed initial combination treatment, they should be transitioned to single-agent oral treatment to prevent relapse from surviving Bacillus anthracis spores.

Antitoxins

An antitoxin should be added to combination antibiotic treatment for any patient for whom there is a high level of clinical suspicion for systemic anthrax. Given that systemic anthrax has a high case-fatality rate and the risk for antitoxin treatment appears to be low, the potential benefit achieved by adding antitoxin to combination antibiotic treatment outweighs the potential risk.

Currently there are 2 antitoxins in the CDC Strategic National Stockpile: raxibacumab and Anthrax Immune Globulin Intravenous (AIGIV). Both antitoxins inhibit binding of Protective Antigen (PA) to anthrax toxin receptors and translocation of the 2 primary toxins (Lethal Toxin (LT) and Edema Toxin (ET)) into cells.

Raxibacumab

Raxibacumab is a recombinant, fully humanized, IgG1λ monoclonal antibody. It appeared safe and well tolerated in 333 healthy adults who received the recommended dose of 40 mg/kg.

Most adverse events were transient and mild to moderate in severity. Pruritis was noted in 2.1% of persons treated with raxibacumab and in none treated with placebo. Although raxibacumab has not been given to patients with systemic anthrax, it is FDA-approved for postexposure prophylaxis PEP and treatment for anthrax under the Animal Rule Summary

Anthrax Immune Globulin

AIGIV is a human polyclonal antiserum made from plasma of persons immunized with Anthrax Vaccine Absorbed (AVA), which might have some direct effect on Lethal Factor (LF) and Edema Factor (EF). It was evaluated in 74 healthy adult volunteers and appears safe and well tolerated at all doses tested.

The most frequently reported adverse events were headache pharyngolaryngeal pain, and nausea.

AIGIV is not FDA approved and could be made available under an Investigational New Drug protocol or an Emergency Use Authorization during a declared emergency.