Rationale:

• Resistant B. anthracis has been engineered in the laboratory.
• Combination therapy is a reasonable therapeutic approach in life-threatening disease with anthrax.
• Treatment for 60 days is justified because of the risk of possible delayed germination of B. anthracis.
• Although ciprofloxacin penetrates the CSF better than doxycycline, it should not be used alone to treat anthrax meningitis because it reaches a CSF concentration of only 10% serum concentration. Penicillin, chloramphenicol, and rifampin penetrate the CSF better than ciprofloxacin.
• Early treatment before test results are available will improve chance of survival.

Evidence:

• Following the 2001 anthrax attacks, patients with inhalational anthrax had a greater chance of survival if they were treated with two or more iv antibiotics (28).
• An animal study shows theoretically that clindamycin may decrease toxin production by B. anthracis (50).
• B. anthracis resistant to penicillin, tetracycline, and ofloxacin have been engineered in the laboratory (16; 51).

Comments:

• When the patient is stable, iv antibiotics can be switched to oral antibiotics to finish the course of therapy. Ciprofloxacin is an excellent choice as an oral agent because its bioavailability is 70% to 80%.