Misuse of Antibiotics Creating Drug-Resistant Tb Strains

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A new study shows that misuse of a popular antibiotic is creating drug-resistant strains of tuberculosis, or TB, a bacterial respiratory disease that the World Health Organization says kills two million people worldwide each year.


Although TB is curable, treatment requires at least six months of continuous therapy using several drugs at once. Researchers have been hopeful that a class of antibiotic drugs called fluoroquinolones [pron. floor-oh-KWIN-oh-loans] could help change that. But Rose Devasia [deh-VAHZ-ee-ah], an infectious disease researcher at Vanderbilt University, says the effectiveness of these safe, easy-to-take drugs has led to widespread overprescribing for a wide range of illnesses, sometimes even before it's known what kind of infection is being treated. That, says Devasia, can cause problems when patients actually have tuberculosis when patients go to an emergency room and they have a cough. The physician thinks, Oh, it's probably pneumonia. I'm going to give him a fluoroquinolone. The fluoroquinolone partially [treats] the TB. He feels good for about 10, 12, 13 days, but then the cough comes back. So he goes to another physician or he goes back to another emergency room. He says, I've got this cough. He gets another course of fluoroquinolones.

Devasia says each time a patient with undiagnosed tuberculosis is treated for the wrong disease using fluoroquinolones, it increases the risk that he'll develop fluoroquinolone-resistant TB.

In a new study published in the American Journal of Respiratory and Critical Care Medicine, Devasia and her colleagues found that nearly one in five tuberculosis patients had received fluoroquinolones in the year before they were diagnosed with TB. A typical course of fluoroquinolones is about 10 days. For every additional 10 days a patient took the medications, the odds of developing fluoroquinolone-resistant TB increased by 50 percent.

In many developing-world pharmacies, fluoroquinolones are easily available without a prescription, under names such as Cipro and Levaquin, and they're used to treat everything from diarrhea to pneumonia.