A new online campaign is putting pressure on fast food giant McDonald's to impose a global ban on products from animals treated with antibiotics.
Scientists warn that treating livestock with antibiotics will lead to a rise in drug-resistant superbugs.
The charity ShareAction has called on consumers to email McDonald's chief executive Steve Easterbrook.
Last week, the fast food chain stopped using poultry treated with antibiotics - but only in its US restaurants.
ShareAction has called on McDonald's - the world's biggest fast food chain - to stop using chicken, beef, pork and dairy products that have been given antibiotics in all of its 30,000 stores globally.
Medical experts warn that the routine use of antibiotics to promote growth and prevent - rather than treat - illness in farm animals contributes to the rise of drug-resistant "superbug" infections. They are said to kill at least 23,000 Americans a year and represent a significant threat to global public health.
Fast food restaurants have become a focal point for change in the food industry by forcing suppliers to change their practices.
According to ShareAction, more than 70% of all antibiotics used in the US are given to livestock.
'Supersize their ambition'
In the UK, that figure stands at more than 50% according to the group.
"We hope this action will encourage McDonald's to supersize their ambition," said ShareAction chief executive Catherine Howarth.
McDonald's told the Reuters news agency that it was too early to set a timeline for phasing out the use of all meat and milk products from animals treated with antibiotics.
The company cited varying practices and regulations around the world as one of the difficulties, but added that it "continues to regularly review this issue".
Rival fast food groups are also under pressure to take action.
On Thursday KFC was the target of a petition from consumer groups that called on the chicken chain to stop using poultry products treated with antibiotics.
KFC has already said it will limit the use of human antibiotics in its chicken by next year.
However, critics claim the policy still allows for routine use of antibiotics by its chicken suppliers.
US burger chain Wendy's plans to stop using chickens raised with antibiotics by 2017 and also plans to set similar goals for pork and beef.