The White House opened its first summit Tuesday to fight antibiotic resistance, and President Obama kicked off the day-long, mostly-closed-door meeting by directing federal departments and agencies to begin a process to buy meat and poultry raised with "responsible antibiotic use."

In an announcement the White House posted Tuesday, it said that the General Services Administration (GSA) will be looking for vendors to offer antibiotic-free meat and poultry as an option in government cafeterias that it manages. The administration set 2020 as the deadline for each agency to create "a preference" for awarding such contracts, to the extent that they're available and cost-effective.

The Presidential Food Service, which provides food to the president and his family, caters state dinners and operates the White House dining rooms, is also committing to serving meats and poultry that have not been treated with hormones and antibiotics.

The Food and Drug Administration also announced Tuesday that it has finalized changes to a regulation laying out what veterinarians must do when they authorize the use of antibiotics to livestock.

Tuesday's gathering included representatives from more than 150 food companies, retailers, pharmaceutical and agricultural companies, hospitals, research firms and some consumer advocacy groups.

While consumer groups praised the federal government for "flexing its considerable purchasing power to help build the market for meat and poultry produced with so-called 'responsible' use of antibiotics," the Natural Resources Defense Council said in a statement that the federal government needs to do more to ensure that antibiotics are used only to treat sick animals and control disease outbreaks.

The summit comes at a time when some retailers and chicken producers have pledged to eliminate the use of antibiotics in their food and operations. In April, Arkansas-based Tyson Foods pledged to phase out antibiotics by September 2017 in its U.S. operations.

Perdue, McDonald’s, Chick-fil-A and Pilgrim’s have all announced steps to scale back their use of antibiotics. Companies such as Panera Bread, Chipotle, Whole Foods and Applegate have also sworn off antibiotics.

Tuesday's event follows the White House plan announced in March to combat antibiotic-resistant bacteria, a mounting problem that causes an estimated 2 million illnesses and 23,000 deaths every year in the United States.

That plan outlined specific goals to fight the spread of antibiotic-resistant microbes over the next five years. They include steps to prevent and contain antibiotic-resistant infections through better surveillance of "superbugs" in hospitals and other health-care settings, to maintain the effectiveness of current and new drugs, and to develop next-generation therapeutics.

In recent years, the overuse of antibiotics in the meat supply has taken on a higher public profile as health officials and consumer groups have issued more and more dire warnings about the potential consequences.

The FDA has been moving to eliminate the use of antibiotics in animals for production purposes, such as merely to make animals grow faster. The changes announced Tuesday focus on the therapeutic uses in feed and water under the supervision of licensed veterinarians. Animal producers will need to obtain authorization from a licensed veterinarian to use the medications to prevent, control or treat a specifically identified disease, said Michael Taylor, the agency's deputy commissioner for foods and veterinary medicine, in a blog post Tuesday. The agency said the rule will go into effect in 120 days.

Scientists, doctors and other public health officials have increasingly warned that if antibiotic resistance were to continue at the current rate, routine infections could become life-threatening. Common modern surgeries and treatments, such as knee replacements, organ transplants and cancer treatments, could  again become dangerous because of hard-to-treat infections. Vulnerable hospital patients and nursing home residents could be at particularly high risk for contracting deadly infections.