By Emma Hitt, PhD

ATLANTA, GA (Reuters Health) – For post-exposure anthrax prophylaxis in children and breastfeeding mothers, amoxicillin may be an alternative to ciprofloxacin or doxycycline, according to the US Centers for Disease Control and Prevention.

Interim recommendations for antimicrobial prophylaxis of children and breastfeeding women, as well as for treatment of children with anthrax, appear in the November 16th issue of the CDC's Morbidity and Mortality Weekly Report.

According to the CDC, the use of ciprofloxacin or doxycycline has been linked to adverse effects in children, and in breastfeeding women little is known about the safety of long-term use of ciprofloxacin or doxycycline (or other tetracyclines).

So far, the US Food and Drug Administration has approved the use of ciprofloxacin, doxycycline, and penicillin G procaine for anthrax prophylaxis, but it has not approved amoxicillin for either the prophylaxis or treatment of anthrax, according to the CDC.

A primary concern is that penicillins do not achieve sufficient intracellular concentrations and are ineffective in killing germinating spores in macrophages. Another concern is that the Bacillus anthracis strain involved in the recent outbreak in the US could reduce the effectiveness of penicillins because it may contain an inducible beta-lactamase.

"Because of these concerns, penicillins, including amoxicillin, are not recommended for initial treatment of anthrax," CDC researchers state, but they add that penicillins "are likely to be effective for antimicrobial prophylaxis following exposure to B. anthracis, a setting where relatively few organisms are expected to be present."

"For the prevention of illness, when we don't have as high a titer as we would in someone who actually had infection, amoxicillin is a good option for people unable to take ciprofloxacin or doxycycline," Dr. Julie Gerberding, Acting Deputy Director of the CDC's National Center for Infectious Diseases, said during a telephone press briefing.

She also noted that a breastfeeding woman exposed to airborne B. anthracis should participate in a post-exposure prophylaxis treatment regimen, in the same way as anyone else.

"Safety concerns [about using antimicrobials] for the developing infant have to be balanced against the treatment to protect both the mother and the baby," Dr. Gerberding told Reuters Health.

Regarding treatment of infants and children, for those with inhalational or systemic anthrax (including gastrointestinal or oropharyngeal anthrax), the CDC recommends intravenous ciprofloxacin or doxycycline, in addition to one or two other antimicrobial agents.

"If meningitis is suspected, ciprofloxacin might be more effective than doxycycline because of better central nervous system penetration," CDC researchers note.

For localized cutaneous anthrax in infants and children, ciprofloxacin or doxycycline should be the initial treatment, they advise. For cutaneous anthrax with systemic involvement, extensive edema, or lesions on the head or neck, the CDC recommends intravenous therapy with multiple antimicrobial agents.

The CDC also presents guidelines for the treatment of children after clinical improvement and guidelines on how breastfeeding mothers can prevent transmission of antibiotics through their milk.

Morbidity and Mortality Weekly Report 2001;50:1014-1016.