Immune: A Journey Into the Mysterious System That Keeps You Alive

by Philipp Dettmer

Let us use this moment to explain how antibiotics work. Like Prometheus who stole fire from the gods and gave it to humanity and made it more powerful, scientists stole antibiotics from nature to make it live longer. In the wild, antibiotics are typically natural compounds that microbes use to kill other microbes. Basically the swords and guns of the microworld. The first successful antibiotic, penicillin, is a weapon from the mold Penicillium rubens that works by blocking bacteria’s ability to make cell walls. As a bacterium tries to grow and divide it needs to produce more cell walls and Penicillium has a shape that interrupts this construction process and prevents the bacteria from making more of itself. The reason why you can safely be treated with penicillin is that your cells don’t have cell walls! Your cells are lined with membranes, which is a fundamentally different structure, so the drug doesn’t do anything to your cells.