Indiscriminate use of anthrax drugs may backfire

NEW YORK, Nov 02 (Reuters Health) - As cases of anthrax infection and contamination mount in the US, health experts are warning the public that taking Cipro and other antibiotics on a just-in-case basis could lead to trouble.

They warn that these anthrax-fighting drugs carry infrequent but sometimes serious side effects, and that indiscriminate use of antibiotics by the public could leave them vulnerable to other infections the drugs are used to treat.

This phenomenon known as antimicrobial resistance can occur when bacteria are repeatedly exposed to a given drug, allowing the bugs to mutate into strains that thwart the treatment. Many disease-causing bacterial strains are already resistant to long-used antibiotics like penicillin.

So far, anthrax strains isolated from the recent US patients have proven susceptible to a range of antibiotics, but the possibility that anthrax could begin to develop resistance cannot be excluded, UK doctors report in the November 3rd issue of the British Medical Journal.

More immediately, health officials worry that infections commonly treated with drugs like Cipro (ciprofloxacin), doxycycline and penicillin will become resistant to the drugs if people were to use them indiscriminately due to anthrax scares.

"The important thing is to ensure that (preventive) treatment is given only to those who really need it, and to discourage its mass use by an understandably alarmed public," write Dr. C. Anthony Hart of the University of Liverpool, and Dr. Nicholas J. Beeching of the Liverpool School of Tropical Medicine.

Their caution follows on the heels of a warning this week from a World Health Organization official that needless use of anthrax-fighting antibiotics could do more harm than good. Only people who are believed to have been potentially exposed to anthrax spores should take preventive antibiotics.

Whenever a person takes antibiotics, the many harmless bacteria that normally dwell in the body are also exposed. Using the drugs unnecessarily also needlessly exposes these good bacteria, which may respond by developing resistance. The problem is that they can transfer this resistance to infectious bacteria, note Hart and Beeching.

Already, the authors point out, the effectiveness of antibiotics in the same class as ciprofloxacin has been compromised due to overuse.

In addition, they add, although usually safe, ciprofloxacin has been associated with tendon ruptures and psychiatric effects--particularly in the elderly--and, more commonly, symptoms including nausea, headache and stomach pain. In most countries, it is not approved for pregnant women or children.

"Indiscriminate use of antibiotics can induce resistance in B. anthracis (the anthrax-causing bacterium) and other organisms," Hart and Beeching write. "To induce antimicrobial resistance on a mass scale would be an even greater triumph for the terrorists."

SOURCE: British Medical Journal 2001;323:1017-1018.

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