Most food chains are failing this crucial test - here's how the biggest restaurants in the US measure up

Even as some restaurant chains move to ditch antibiotics - in part due to customer backlash over the overuse of the drugs - most restaurant chains are still failing to make changes.

There's evidence that antibiotic overuse is contributing to the rise of super-strong bacteria that no longer respond to antibiotics, something that could contribute to the rise of untreatable superbugs in the future.

Despite this, 16 out of 25 of the biggest restaurant chains in America received a failing grade in new Chain Reaction report released on Tuesday. The report, compiled by six organizations dedicated to food safety and health, graded chains based on their policies, practices, and transparency regarding antibiotic use in their meat and poultry supply chains.

Companies were given a numerical score (0-100%) and a letter grade (F-A). Here's the full list, ranking chains from the worst to the best.