The overuse of antibiotics has caused three kinds of bacteria - one that causes life-threatening diarrhea, one that causes bloodstream infections and one that transmits sexually - to become urgent threats to human health in the United States, federal health officials say in a landmark report out Monday.

The report from the federal Centers for Disease Control and Prevention (CDC) is the first to categorize the threats posed by such germs in order of immediate importance, from ‘urgent,’ to ‘serious,’ to ‘concerning.’ It is also the first to quantify the toll of such so-called superbugs, saying they cause at least 2 million infections and 23,000 deaths each year.

‘It’s not too late’ for the nation to respond, rein in the infections and keep antibiotics working by reserving them for when they are truly needed, but several steps must be taken right away, CDC Director Tom Frieden said Monday. ‘If we are not careful and we don’t take urgent action, the medicine cabinet may be empty for patients with life-threatening infections in the coming months and years.’

On the urgent list: