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By challenging E. coli with sublethal norfloxacin for 10 days, Henry Lee and James Collins suggests the bacterial altruism leads to the population-wide resistance. By detailedly analyzing experiment data, we suggest that bacterial cooperation leads to population-wide resistance under norfloxacin pressure and simultaneously propose the bacteria shield is the possible feedback mechanism of less resistant bacteria. The bacteria shield is that the less resistant bacteria sacrifice the large number of themselves to consume norfloxacin and then to relieve the norfloxacin burden from highly resistant bacteria. Thus, due to highly resistant bacteria and less resistant bacteria extracted from the same bacteria population, bacterial cooperation leads to heteroresistance.
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