Antibiotics have been battling bacteria and saving lives since the 1940's. Fast forward several decades, however, and the war is changing.

"Superbugs" are strains of bacteria that have become resistant to antibiotics, and they have been gaining strength and shifting the tide in their favor.

"This is really a frightening situation," Dr. Beth Bell of the CDC told CNBC's "On The Money" in a recent interview, "and really one of the most serious infectious disease threats of our time. "

CDC data show superbugs cause infections in at least two million people in the U.S. each year, and kill 23,000. Barely a week ago, in a landmark meeting, the United Nations General Assembly voted to take a coordinated approach to antibiotic resistance as a global health crisis.

By 2050, superbugs could kill 10 million people, according to the Review of Antimicrobial Resistance.

Bell, who oversees the CDC's emerging infectious disease programs, told CNBC that "in other parts of world, there are bacteria that are resistant to all known antibiotics."

If current antibiotics become ineffective, doctors will be unable to stop infections, she added.

"Antibiotic resistance and the rise of superbugs really [do] put modern medicine at risk," Bell explained.

"If you think about some of the main advances in medicine over the last number of decades, for example, cancer chemotherapy, organ transplantation, joint replacements, the success of all these innovations is really based on our ability to treat infections," she added.