Study finds how bacteria fight antibiotics

Champaign, Ill. -- U.S. scientists say they've discovered how some bacteria survive antibiotic treatment -- they turn on resistance mechanisms when exposed to the drugs.

"When patients are treated with antibiotics some pathogenic microbes can turn on the genes that protect them from the action of the drug," said University of Illinois Professor Alexander Mankin, associate director of the school's Center for Pharmaceutical Biotechnology and the study's principal investigator. "We studied how bacteria can feel the presence of erythromycin and activate production of the resistance genes."

Erythromycin and other macrolide antibiotics act upon the ribosomes -- the protein-synthesizing factories of the cell, the researchers said. A newly made protein exits the ribosome through a tunnel spanning the ribosome body.

Antibiotics can ward off an infection by attaching to the ribosome and preventing proteins the bacterium needs from moving through the tunnel, they said.

But the study reveals some bacteria have learned how to sense the presence of the antibiotic in the ribosomal tunnel, and in response switch on genes that make them resistant to the drug, Mankin said.

The study that included Assistant Professor Nora Vazquez-Laslop and undergraduate student Celine Thum appears in the April 24 issue of the journal Molecular Cell.

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