During the anthrax attacks of 2001, persons with inhalational anthrax treated with two or more antibiotics active against B. anthracis had a greater chance of survival. Thus, two or three antibiotics in combination are recommended for treatment of persons with inhalational anthrax, and these should ultimately be based on susceptibility testing. Treatment should continue for 60 days, since this has been the maximum time required for germination of spores acquired through inhalational exposure. A switch from intravenous to oral formulations can occur once clinical improvement is demonstrated.
Adult patients with cutaneous anthrax can be treated with oral ciprofloxacin (500 mg twice daily). If the strain is susceptible, oral doxycycline (100 mg twice daily) or amoxicillin (500 mg three times daily) may also be used. When cutaneous anthrax occurs in the setting of a bioterrorist event, treatment should continue for 60 days (because of the risk of inhalational exposure) as opposed to 7 to 10 days for naturally acquired disease.
An anthrax vaccine (BioThrax, BioPort), consisting of a noninfectious sterile filtrate from the culture of an attenuated strain of B. anthracis, has been approved for preexposure prophylaxis. The Food and Drug Administration has recently approved the release of the vaccine by the manufacturer’s (BioPort) newly renovated facility. Vaccination consists of six 0.5 mL subcutaneous doses given at 0, 2, and 4 weeks and then 6, 12, and 18 months after exposure. Annual boosters are recommended for continued immunity. Mainly minor adverse effects (local erythema and tenderness, fever, myalgias) related to its use have been reported. Currently, routine preexposure vaccination is limited to military personnel. Postexposure prophylaxis with the anthrax vaccine has not yet been approved by the Food and Drug Administration but is under investigation.
If public health officials have determined that there is evident risk of exposure to anthrax, postexposure prophylaxis is necessary to prevent clinical disease. A total of 60 days of therapy is recommended for postexposure prophylaxis. However, owing to the unusually high potency of anthrax spores used in the bioterrorist attacks of 2001 and the theoretical possibility that weaponized spores might cause illness up to 100 days after exposure, the CDC has asked that clinicians caring for patients exposed to anthrax consider these additional recommendations: (1) an additional 40 days of antimicrobial prophylaxis (for a total of 100 days) and (2) administration of three doses of anthrax vaccine on days 0, 14, and 28.