PHOENIX - Does your favorite restaurant use antibiotics?

It's a topic getting a lot of attention, after the United Nations called the practice a "global health crisis on par with AIDS."

To date, more than half of the 25 largest chains have antibiotics policies in place. The number has tripled in just three years.

So why is this important?

"Overuse is a really big threat to public health," said Julia Calderone, the health editor for Consumer Reports. "It can lead to antibiotic resistant bacteria and that can make infections in humans really difficult to treat."

All of the progress at chain restaurants is due to changes in chicken policies.

The changes to no antibiotics in beef and pork is still very limited.

So who passed with flying colors?

According to Consumer Reports, Panera Bread and Chipotle came out ahead because nearly all of their meat and poultry are raised without antibiotics.

Chick-fil-A, Taco Bell, Subway and Wendy's earned B's and C's.

KFC improved with a B- and McDonalds pulled in a C+.

But while KFC says it is committed to serving chicken raised without antibiotics, those changes won't be implemented for a while.

All of the chicken served at McDonalds has been raised without medical antibiotics, but the company has made no progress with its beef and pork.

"We are definitely noticing a shift. Consumers are becoming more aware of the potential dangers of overusing antibiotics," Calderone said.