Anthrax Scare Raises Concerns About Antibiotic Resistance

Edition: December 2001 - Vol 9 Number 12
Article#: 1112
Author: Repertoire

Scares about anthrax and mass prescribing of ciprofloxacin (sold as Cipro by Bayer AG) could backfire, warned the authors of an editorial in the British Medical Journal (''Prophylactic treatment of anthrax with antibiotics,'' BMJ 2001, 323:1017-1018.)

''The important thing is to ensure that prophylactic treatment is given only to those who really need it, and to discourage its mass use by an understandably alarmed public,'' said the authors, C. Anthony Hart, professor of medical microbiology at the University of Liverpool, and Nicholas J. Beeching, senior lecturer in tropical medicine, the Liverpool School of Tropical Medicine. ''Indiscriminate use of antibiotics can induce resistance in B anthracis and other organisms,'' said the authors.

B anthracis is sensitive in vitro to a range of antimicrobials, including penicillin, amoxicillin, doxycycline, tetracycline, clarithromycin, clindamycin, and ciprofloxacin, say the authors. Although benzylpenicillin is the treatment of choice, the fact is, treating anthrax after inhalation of spores is particularly difficult, because the disease progresses rapidly to death. This has led to the introduction of chemoprophylaxis for individuals at risk.

In animal models, penicillin, ciprofloxacin, or doxycycline given 24 hours after exposure to a lethal aerosol provided significant protection against death, they say.

Currently oral ciprofloxacin is recommended after known exposure to spores. Disease can present 50days or more after exposure, so prophylaxis should continue for 60days unless exposure has been excluded, the authors say. But using antimicrobials prophylactically could induce side effects in users as well as resistance in bacteria.

Antimicrobials need to be used according to national guidelines after appropriate assessment of risk, especially when prolonged use is intended. Although generally safe, ciprofloxacin is associated with rupture of tendons and neuropsychiatric disorders, especially in elderly people. In most countries it is not licensed for use in pregnancy or children. In children, the concern is damage to the cartilage in weight bearing joints -- seen when treating juvenile beagle dogs. Few data exist on use of ciprofloxacin in pregnancy, and here amoxicillin might be safer, say the authors.