Steve Easterbrook, the new CEO of McDonald’s, is firing on all cylinders in his bid to reverse his company’s latest decline in revenues. The fast food giant’s recent announcement that it will stop selling chicken raised with antibiotics that are important for human medicine is both a smart marketing move and an effort to provide safe and healthy food, according to experts. The company said it would implement that policy over the next two years across its 14,000 U.S. restaurants. Easterbrook, who assumed his new role in January, is credited with turning around the fortunes of McDonald’s in the U.K. over the past several years. He calls himself an “internal activist” and is changing the way his company is perceived, noted Jason Riis , visiting marketing professor at Wharton. “He sees McDonald’s as a modern and progressive burger and breakfast restaurant,” he said.…