When Alexander Fleming came back from a Scottish vacation in the summer of 1948 to find his London lab bench contaminated with a mold called Penicillium notatum, he kicked off a new age of scientific sovereignty over nature. Since then, the antibiotics he discovered and the many more he inspired have saved millions of lives and spared immeasurable suffering around the globe. But from the moment it started, scientists knew the age of antibiotics came stamped with an expiration date.

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