Tyson Foods says it has already reduced its use of human-use antibiotics by 80 percent over the past four years. Here, Tyson frozen chicken on display at Piazza's market in Palo Alto, Calif., in 2010. Paul Sakuma/AP hide caption

itoggle caption Paul Sakuma/AP

The European Union banned the use of antibiotics to boost animals' growth in 2006. At first, the ban had little effect on the amount of drugs given to pigs. Carsten Rehder/Corbis hide caption

itoggle caption Carsten Rehder/Corbis

An order of McDonald's Chicken McNuggets in Olmsted Falls, Ohio. McDonald's says it plans to start using chicken raised without antibiotics important to human medicine. Mark Duncan/AP hide caption

itoggle caption Mark Duncan/AP

An overgrowth of Clostridium difficile bacteria can inflame the colon with a life-threatening infection. Dr. David Phillips/Getty Images/Visuals Unlimited hide caption

itoggle caption Dr. David Phillips/Getty Images/Visuals Unlimited

One form of carbapenem-resistant bacteria seen in culture. CRE bacteria are blamed for 600 deaths a year in the U.S. and can withstand treatment by virtually every kind of antibiotic. CDC hide caption

itoggle caption CDC

You don't want to run into methicillin-resistantStaphylococcus aureus (MRSA) bacteria. A potential new antibiotic could help fight this bug. CDC hide caption

itoggle caption CDC

Yes, you could do this at home. Growing bacteria you find in a pile of dirt or a local pond might reveal the next big antibiotic. Charlotte Raymond/Science Source hide caption

itoggle caption Charlotte Raymond/Science Source

Young broilers nibble feed at a chicken farm in Luling, Texas. The Food and Drug Administration has issued new guidance on how drug companies label antibiotics for livestock. Bob Nichols/USDA/Flickr hide caption

itoggle caption Bob Nichols/USDA/Flickr

Turkeys sit in a barn in Sonoma, Calif. An estimated 46 million turkeys are cooked and eaten during Thanksgiving meals in the U.S. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

In recent years, pork producers have found ways to keep the animals healthy through improved hygiene. M. Spencer Green/AP hide caption

itoggle caption M. Spencer Green/AP

Cattle crowd inside a feedlot operated by JBS Five Rivers Colorado Beef in Wiley, Colo. John Moore/Getty Images hide caption

itoggle caption John Moore/Getty Images