Tetracycline, one of the most-used antibiotics in the world, is losing its effectiveness against common bacterial infections, experts say. Growing bacterial resistance to the drug, which for 40 years was a first-line defense against respiratory, urinary and genital-tract infections, is making tetracycline the Model T of antibiotics.
"We no longer have a magic bullet," said Dr. Marilyn Roberts, a pathologist at the University of Washington. Studies there show tetracycline-resistant bacteria prevalent even in women who have no recent exposure to the drug.
Roberts says the presence of such organisms means tetracycline may no longer be useful for the control of urogenital tract infections like gonorrhea and chancroid, which causes genital ulcers.
There are also reports in the United States and Britain that tetracycline no longer will kill the germs that cause meningitis and respiratory infections. And some U.S. researchers say the drug is losing effectiveness against some kinds of pneumonia.
Tetracycline still works against many infections, including the organisms that cause Lyme arthritis, Rocky Mountain spotted fever and Chlamydia pneumoniae, an acute upper-respiratory disease.
But a growing number of patients with resistant germs are having to return to their doctors and have another antibiotic prescribed _ often one that costs more and may add unwanted side effects.
Health experts say tetracycline's declining effectiveness is particularly disturbing in light of microbes' resistance to other antibiotics such as penicillin and erythromycin, which is widely used to treat respiratory infections.
The first signs of rapidly spreading tetracycline resistance appeared in 1983, when a new, resistant strain of gonorrhea surfaced.
Dr. Stuart Levy, a microbiologist at the Tufts University School of Medicine, says resistant strains now make up many of the 600,000 gonorrhea cases each year.
"Tetracycline is no longer useful in gonorrhea," Levy said. "And if the trend continues, the drug may no longer be useful in other diseases _ a drug that has a history of fantastic success."