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Crop Biotech Update

Duke Scientists Explain Antibiotic Tolerance of Bacteria

October 24, 2012

Duke University scientists discovered the explanation on one great irony of life—how antibiotics lose their power to kill bacteria. The researchers used molecular biology and mathematical modeling to understand the mechanism behind the tolerance as well as the influence of inoculum effect in the efficacy of treatment. The inoculum effect states that "for any dosage of antibiotic, its ability to kill bacteria decreases as the bacterial population rises."

According to Lingchong You, one of the authors of the study, the inoculum effect is caused by the bistable inhibition of bacterial growth. Bistability refers to the state in which a cell or population has the potential to live in two states at the same time, with its actions depending on which state it is when stimulated. The results of their study suggest that an important requirement for the said bistability is the rapid degradation of the ribosome induced by the antibiotics. When fast degradation of ribosomes occurs, the recovery of bacterial growth after treatment is hampered, which has a critical effect on the determination of timing of antibiotic use for effective treatment of bacterial infections.