>>“misuse” meaning using them to treat viral infections

I suspect the amount of antibiotics used for that could be measured in kilograms while the amount used in animal husbandry to promote growth (and to allow animals to be kept in close quarters e.g. CAFOs) is measured in metric tons. The obvious solution is to impose a tax just slightly higher than the profit to be gained by improved growth rates which would not be enough to really impact prices on drugs used for infections - but no country has done this (so far as I know).

Here's hoping that teixobactin turns out to be effective as an antibiotic - and does NOT promote rapid growth.