Why does feeding livestock routine low doses of antibiotics worry clinicians?

1. In the United States, 70 percent of the antibiotics produced are fed to animals. 2. Those antibiotics are given in low doses rather than full therapeutic ones. 3. Low doses maximize the probability that resistance develops, because they select survivors without wiping the population out. 4. The resistant bacteria that emerge are readily transferred to humans. 5. A dose that killed every gut bacterium would leave nothing to select, so the second option describes the opposite risk. 6. Antibiotics never worked against viruses in the first place, so livestock dosing changes nothing there. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 22 "Prokaryotes: Bacteria and Archaea", section 22.4 Bacterial Diseases in Humans_