Gov. Jerry Brown of California has signed a bill — the toughest in the country — to prohibit the use of antibiotics in livestock unless a veterinarian prescribes the drugs to treat a disease or infection.

Farmers in that state will no longer be able to use antibiotics to “bulk up” animals or make them fatter, a practice the Food and Drug Administration has long discouraged.

Related: Food Additives: Are They Safe, or Can They Make Us Sick?

In his signing message, Brown called the over-use of antibiotics in livestock “an urgent problem.”

“The science is clear that the overuse of antibiotics in livestock has contributed to the spread of antibiotic resistance and the undermining of decades of life-saving advances in medicine,” Brown said.

According to the Centers for Disease Control and Prevention (CDC), using antibiotics in livestock to make animals fatter contributes to human antibiotic resistance in these ways:

  • Antibiotic-resistant bacteria thrive in farm animals while vulnerable bacteria die off.
  • Humans can get the resistant bacteria from the animals we eat as food.
  • The animals we eat as food can also transmit antibiotic-resistant infections.

Antibiotic resistance means bacteria are finding a way to “resist” or fight many first-line antibiotics, so that many drugs that used to kill germs may no longer do so. In the United States, at least 2 million Americans develop antibiotic-resistant infections — such as MRSA — annually, and 23,000 people a year die as a result, according to the CDC.

The World Health Organization (WHO) has called antibiotic resistance a global emergency. "The world is headed for a post-antibiotic era, in which common infections and minor injuries which have been treatable for decades can once again kill,” says Keiji Fukuda, MD, MPH, WHO’s assistant director-general for health security.

Antibiotic resistance "has cast a shadow over the medical miracles we take for granted,” according to the Alliance for the Prudent Use of Antibiotics (APUA), a research and education organization. “If resistance to treatment continues to spread, our interconnected, high-tech world may find itself back in the dark ages of medicine, before today’s miracle drugs ever existed."

To help prevent antibiotic-resistant infections, the CDC advises consumers to follow food safety precautions to avoid ingesting bacteria and use antibiotics carefully (including never sharing the drugs and always finishing the entire course of antibiotics, even if you feel better).

Avoiding meat that contains antibiotics

Consumer Reports and other consumer advocacy groups are pushing restaurants and fast-food chains to use meat and chicken that contains no antibiotics. Some chains are already doing so. If you want to buy antibiotic-free meat and chicken for your own kitchen, you can take these steps while shopping.

Look for the label “USDA Organic.” The U.S. Department of Agriculture’s rules for organic food prohibit antibiotic use in livestock.

Related: Grass-Fed Beef: Worth the Prime Price?

Look for the label “No antibiotics added” on meat and chicken. According to Consumer Reports, this label is most reliable when accompanied by a "USDA Process Verified" shield or a label from a private certifier such as the Global Animal Partnership. This means the company paid to have the agency or a private certifier verify the claim.

Don’t rely on labels that say “Natural.” This means that the meat or chicken contains no added color or artificial ingredients and is only minimally processed, according to the USDA. It doesn’t mean it is antibiotic-free.

Ditto for labels that say “Antibiotic-free.” The USDA does not endorse this label, so Consumer Reports suggests you ignore it.

Related: 5 Common Antibiotic Mistakes

Diana is an award-winning writer and editor with more than 20 years' experience in magazine, video, book and digital journalism, with a specialty in health coverage. She was a longtime writer and news editor at the Center for Investigative Reporting; has written for publications from the Washington Post to the Times of London syndicate; and has served as a senior and/or consulting editor at Time Inc. Health, Hippocrates, HealthDay News Service and Reporting on Health. She was also editor in chief of Consumer Health Interactive, a national health and medical web site, and has reported on finance for Blueshift Research and PBS Frontline. Before joining SafeBee, she was editor of Bioenergy Connection, a national magazine about bioenergy at UC Berkeley. Her favorite safety tip: Wear a bike helmet.