Yet, the unfortunate reality is that the longstanding challenge of drug resistance is cause for concern and action. Bacteria have been developing resistance to powerful antibiotics ever since the drugs were first introduced in the 1930s. In some cases, bacteria developed widespread resistance in years and sometimes months after a new drug came out. And bacteria are building up ever more extensive immunity thanks to current practices of overusing and misusing the drugs—antibiotics given thoughtlessly for mild illnesses, or used to treat viral infections (which antibiotics don’t fight), or poured into the feed of healthy livestock. Coupled with the sluggish development of new drugs in the past few decades, the public health problem has reached a crisis level.