As a microbiologist and member of the US Congress, I applaud your call to action on the overuse of antibiotics in agriculture (Nature 499, 379, 394–396, 398–400; 2013). I have been fighting since 1999 to pass the Preservation of Antibiotics for Medical Treatment Act (PAMTA), which would ban the use of eight classes of medically important antibiotics in agriculture, with exceptions for treating sick animals.

In the United States, antibiotics are often distributed at sub-therapeutic doses to healthy farm animals to compensate for crowded and unsanitary living conditions or to promote growth.

In June, science ministers from the G8 nations discussed antibiotic resistance and committed to clamping down on overuse of antibiotics in health care, farming and fisheries. It is only through such coordinated international action that we can begin to hold back the tide of antibiotic-resistant bacteria.

Policy-makers need help, as you point out. I urge US readers to take a stand on this issue and ask their representatives and senators to co-sponsor PAMTA in the House of Representatives or the Preventing Antibiotic Resistance Act in the Senate (see www.louise.house.gov).