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CDC Updates Anthrax Prophylaxis Plan for Pregnant Women

Kate Traynor

The Centers for Disease Control and Prevention (CDC) today described ciprofloxacin as the initial "antimicrobial of choice" for asymptomatic pregnant women who require prophylaxis after exposure to Bacillus anthracis.

For pregnant women with no symptoms of anthrax, the recommended prophylactic dosage of ciprofloxacin is 500 mg, taken orally twice a day for 60 days. Although a limited amount of clinical data exists on ciprofloxacin use during pregnancy, CDC concluded that the drug is "unlikely to be associated with a high risk for structural malformations in fetal development."

The information appeared in the Nov. 2 issue of Morbidity and Mortality Weekly Report (MMWR) (PDF).

When the B. anthracis strain in question is known to be sensitive to penicillin, prophylaxis with amoxicillin—500 mg, taken orally three times a day—may be considered for asypmptomatic pregnant women, said CDC. In making this recommendation, CDC acknowledged that penicillinase activity may be seen in the penicillin-sensitive B. anthracis strain used in the current bioterrorist attack. CDC claimed that penicillin would probably be effective for prophylaxis because "relatively few" B. anthracis bacteria are likely to be present in people undergoing prophylaxis.

CDC does not recommend penicillin monotherapy for the treatment of symptomatic anthrax.

Doxycycline, said CDC, should be used for postexposure prophylaxis in asymptomatic pregnant women only when contraindications exist for the use of other "appropriate" antimicrobials that are effective against anthrax. Use of doxycycline is associated with adverse effects on developing fetal bones and teeth.

A report from last week’s MMWR had advised that doxycycline could be considered for use in pregnant women before six months of gestation to treat "life-threatening" anthrax. The report recommended that doxycycline treatment last no more that 7–14 days in such cases.