WHEN IT comes to familiar icons, McDonald’s ranks high in symbolism around the nation and the world. McDonald’s is also the world’s largest restaurant chain. The company deserves praise for a decision just announced that cannot have been easy to take but is important: to curtail the use of antibiotics in chicken products sold in the United States.

Antibiotics, drugs that fight bacterial infections, came into widespread use after World War II and are now a mainstay of human health. They save lives and enable all kinds of medical advances. But at the same time that antibiotics became known as wonder drugs, bacteria gradually adapted and started to overcome the drugs, a phenomenon known as antibiotic resistance. For several decades, it didn’t seem to be a big problem because new antibiotics were being discovered. But now resistance is reaching crisis proportions and the pipeline of new discoveries has dwindled.

A significant reason for the rise of resistance is overuse of antibiotics in human health. But evidence has also pointed to the widespread use of antibiotics in animal agriculture. Farmers routinely put antibiotics in feed and water for farm animals to stimulate more growth without using more feed, or to prevent disease in a whole flock or herd. This is different from using the drugs for specific sick animals. Evidence suggests that regular use of antibiotics for growth promotion may be driving resistance, too.

McDonald’s announced that over two years it will curtail the use of antibiotics that are considered important to human health in chicken served at its more than 14,000 U.S. restaurants. McDonald’s has wisely adopted World Health Organization guidelines on which antibiotics are covered. The step may have wide impact.

Farmers and ranchers have often argued they are not responsible for the rise of antibiotic resistance and have balked at change. The McDonald’s decision is certain to get their attention and cause change by market incentives. Also, as chicken producers adapt and learn how to keep their flocks healthy without the routine use of antibiotics, the know-how they develop may spread. Of course, the McDonald’s decision is good marketing, too — consumers say they want it. More power to the marketplace.

This is the latest in a string of developments that suggest, at last, a more serious approach to the problem of antibiotic resistance, which the Centers for Disease Control and Prevention say leads to 2 million illnesses and 23,000 deaths a year in this country alone. The Food and Drug Administration has asked antibiotic manufacturers to stop selling the drugs for growth promotion in farm animals (although the FDA would permit continued use for disease prevention) and is giving veterinarians more control. Meanwhile, President Obama has proposed to double funding for combating antibiotic resistance, and the White House has mapped out an ambitious strategy. Bacteria have been evolving and adapting for many years, so it is encouraging to see the government and private sector doing more to address a major public health threat.