Foster Farms, the California-based company linked to an outbreak of multi-drug resistant Salmonella Heidelberg that sickened 634 people in 2013 and 2014, is the latest major chicken producer to go antibiotic-free. The company announced Monday that it is introducing two new lines of antibiotic-free chicken for major retailers in the Western U.S. The new Foster Farms Certified Organic and Foster Farms Simply Raised chickens are produced without any antibiotics. Foster Farms also announced that it has already eliminated antibiotics that are critical to human medicine from all of its chicken production and is working to eliminate the use of all human antibiotics “except in those instances where the clinical health of a flock is at risk.” The company said it will continue to use animal-only antibiotics when needed for conventional flocks, and that an independent auditor will ensure the company sticks with the new objectives. The company says the move makes it the largest producer of USDA-certified organic and antibiotic-free chicken in the West. “Our company is committed to responsible growing practices that help preserve the effectiveness of antibiotics for human health and medicine,” said Ron Foster, CEO and president of Foster Farms. “We take a holistic approach to antibiotic stewardship.” The Foster Farms changes come about a month after Tyson Foods, the largest poultry producer in the U.S., announced that it would strive to quit using human antibiotics in its chicken flocks by the end of September 2017. Last September, Perdue Foods said it has not used antibiotics for growth promotion since 2007 and doesn’t use any human antibiotics in any of its feed. Unlike Perdue and Tyson Foods, Foster Farms has not set a timeline for ending the routine use of medically important antibiotics. The Keep Antibiotics Working coalition said that unless Foster Farms is clearer about that timeline and some of the other details of its use policy, the company’s efforts fall short of the others’.