KFC, the world's largest chain of fried chicken restaurants, may face pressure from consumer and environmental groups to change how the animals it uses are raised after McDonald's Corp said it would switch to chicken raised without human antibiotics.

McDonald's will phase out chicken raised with antibiotics over two years to allay concern that the use of the drugs in meat production has exacerbated the rise of deadly "superbugs" that resist treatment, Reuters reported last week.

Within days, retailer Costco Wholesale Corp told Reuters it also aims to eliminate the sale of chicken and meat raised with human antibiotics.