New Resistance To Anthrax Treatment

Cipro, the antibiotic that became a household word during the 2001 anthrax scare, is becoming increasingly ineffective against other dangerous germs because of overuse, a study found.

The researchers examined data on infections in hospitalized patients in 43 states and Washington, D.C., from 1994 to 2000. Ailments included respiratory and urinary infections caused by a variety of bacteria.

Many germs had grown resistant to fluoroquinolones, a class of antibiotics that includes ciprofloxacin, known by the brand name Cipro.

In 1994, Cipro was effective against 86 percent of the bacteria samples analyzed, but that dropped to 76 percent by 2000, the researchers found.

The anthrax bacterium was not studied, and the researchers said their findings do not mean that Cipro is becoming less effective against anthrax, which rarely affects humans.

The study appears in Wednesday's Journal of the American Medical Association.

"More judicious use of fluoroquinolone antibiotics will be necessary to limit this downward trend," said the researchers, led by Melinda Neuhauser of the University of Houston.

Bacteria that became increasingly resistant during the study were all common causes of infection and included E. coli, Pseudomonas aeruginosa and Klebsiella pneumoniae.

Resistance can develop when a drug is used repeatedly against the same germ, which may eventually mutate to outwit the drug. Overuse and inappropriate use of antibiotics can also cause bacteria that normally live in the body to mutate and become infectious.

The increasing resistance found in the study came at a time when doctors increasingly prescribed Cipro and similar drugs for common ailments, including respiratory infections caused by viruses, which are unaffected by antibiotics, the researchers said.