The ?? ?? ??overuse of antibiotics is probably far from your mind when you order a beef burger from a fast food chain. But it shouldn't be.

A new report out Thursday rates top U.S. restaurant chains like McDonald's, Starbucks, and Chipotle on their commitments to reduce antibiotic use in beef. When you eat beef from a cow given antibiotics, it could impact your health, making you less resistant to certain diseases.

While Chipotle took home the top score because it regularly conducts internal audits of its beef supplies, McDonald's, the single-largest purchaser of beef, got a C. Although, that's up from last year's F. Starbucks got an F because it didn't even bother to fill out a survey about its antibiotics policies for the six major consumer, public health, and environmental organizations that annually release the scorecard.

To prevent livestock raised as meat, known as food animals, from getting sick, many meat producers will give healthy animals antibiotics to help them survive what is often an overcrowded and unsanitary farm.

Antibiotics are supposed to help obliterate disease, but when used excessively they can actually have the opposite effect. Public health and environmental advocates worry that bacteria from these industrial farms can become resistant to antibiotics given to humans, says Lena Brook, lead author of the report called "Chain Reaction V" and director of food campaigns at the Natural Resources Defense Council, an environmental advocacy organization. Brook hopes once a few companies commit to lower their antibiotic use, more will follow.

Infectious disease experts estimate more than 160,000 Americans dieevery year from antibiotic-resistant infections. That's more than four times the fatalities from car accidents and shark attacks, combined. (The CDC pegs annual deaths from antibiotic-resistant infections at 23,000, but some infectious disease researchers contest that number is woefully inaccurate due to poor data.) It's important to note, however, that these infections can't all be traced back to animals that were given antibiotics. Medical environments like hospitals can also be prone to overprescribing antibiotics for humans.

While the FDA bans beef producers from using antibiotics to make their animals grow, the rules aren't always followed. What's more, healthy animals may be given antibiotics to prevent them from getting sick. So your burger may be pumped with antibiotics despite (and even because of) the loose government rules.

"We therefore urge restaurant chains to require their suppliers to go beyond FDA’s minimum requirements and set comprehensive, time-bound policies restricting all routine antibiotic use, in order to make significant progress in curbing antibiotic resistance," the report states.

Popular restaurant chains like McDonald's can help turn the tide on the reduction of antibiotics given to animals — which, in turn, can stem antibiotic resistant infections. And some have. Top restaurant chains in America have significantly committed to reduce the antibiotics they use in chicken. Now the next battle is beef.

Report authors sent surveys to the top 25 restaurant chains (by sales) asking about antibiotic use in all their meat supplies and looked at the chains' public statements about antibiotic use. Of the 25, 21 are included on the beef scorecard as four do not serve beef products. This is the fifth year this scorecard has been released. (A fast casual restaurant offers higher-quality ingredients, nicer dining, and a higher price point than fast food but also combines the speedy service of a fast food restaurant. Think Chipotle or Panera.)

The report also gives some restaurant chains a superlative — either calling out a chain for its inaction or congratulating it.

Make sure to check out where each restaurant stands before your next burger craving hits.

More details on the grades

Both Chipotle and Panera earned high grades, an A and A- respectively, because of both companies' long-standing responsible uses of antibiotics in beef, the report says. The chains early work in responsible antibiotic use earned them both the superlative "Early Leaders." Both have received marks in the A range since the first Chain Reaction scorecard was released in 2015.

Chipotle (fast casual): A

• The Mexican grill restaurant regularly conducts internal audits of their beef supplies, including annual farm inspections, the report says. In 2018, more than one third of Chipotle's beef was certified by either Certified Humane or Global Animal Partnership, which both ensure animal welfare standards.

• Chipotle makes its beef supplier track the type and amount of antibiotics in its beef supply and assesses this information internally, the report says.

• Chipotle reported about half of the beef it served in its U.S. restaurants comes from 100 percent grass-fed producers.

• It also received the "Early Leaders" superlative, given its responsible antibiotic use early on.

Though not mentioned in the report, it's important to mention the closing of a Chipotle restaurant in Ohio in 2018 due to a foodborne illness, affecting 647 people, NPR reported.

Panera (fast casual): A-

• Panera reported that 100 percent of its beef is pasture raised, grass fed and grass-finished in 2019.

• It also received the "Early Leaders" superlative, given its responsible antibiotic use early on.

McDonald's (fast food): C

• McDonald's, the single-largest purchaser of beef, moved up from a F in last year's beef scorecard to a C, given its December 2018 policy that echoes the 2017 WHO guidelines on use of antibiotics in livestock. This earned it the superlative ""Biggest Mooover." WHO's guidelines recommend that farmers and other food producers stop using antibiotics to prevent disease in healthy livestock and to make these animals gain weight.

• McDonald's is promising to audit its beef suppliers and share regular information with the public starting in 2022. The report says, like Chipotle, it requires its supplier to track the type and amount of antibiotics used to produce the company’s beef supplies and assess this information internally.

Subway (fast food): C

• In 2015, Subway committed to providing antibiotic-free beef for U.S. restaurants by 2025. But it hasn't made any progress toward this goal yet, the report says.

• This year, Subway updated their antibiotics policy to follow WHO's guidelines. This policy change helped earn Subway a C but it's important to see if it will put its promises into action, the report says.

Wendy's (fast food): D+

• Wendy’s reported that it currently gets 30 percent of its beef from producers that have cut tylosin, a medically important antibiotic, by 20 percent, the report says.

• Wendy's received the "Biggest Wanna-be" superlative, given its efforts to publicize small changes to antibiotic use in its beef. It also does not say if and when it will curb antibiotic use for the rest of its beef supply, the report says.

Taco Bell (fast food): D

• In July 2019, Taco Bell announced it will cut medically-important antibiotics in its beef by 25 percent by 2025, the report says.

• Although this is a good step forward, the authors of the report don't think this commitment goes far enough. Additionally, Taco Bell does not have a general policy addressing its antibiotic use in beef.

Starbucks (fast food), Burger King (fast food), Domino's (fast food), Sonic (fast food), Olive Garden (fast casual), Buffalo Wild Wings (fast casual), Little Caesars (fast food), Arby's (fast food), Chili's (fast casual), Panda Express (fast food): F

• These chains didn't return surveys sent to them to learn about their antibiotic policies.

Pizza Hut (fast food), Applebee's (fast casual), Dairy Queen (fast food), Jack in the Box (fast food), IHOP (fast casual): F

• These chains completed the surveys, but only stated antibiotic policies for meat other than beef, like chicken or pork.

• All 15 restaurants that failed don't have policies that go beyond FDA Guidance 213, the loophole that lets meat producers use antibiotics on healthy animals to prevent them from getting sick.