(Corrects name to Natural Resources Defense Council in 8th paragraph)

FILE PHOTO: Robert Redfield, Director of the Centers for Disease Control and Prevention, attends an event announcing opioid response grants to state governments in the Roosevelt Room of the White House in Washington, U.S. September 4, 2019. REUTERS/Erin Scott/File Photo

(Reuters) - Nearly twice as many people are dying in the United States from antibiotic-resistant infections than previously believed, U.S. health officials said on Wednesday, as so-called “superbugs” alarm experts with their rate of growth and spread.

Issuing its first comprehensive report into the growing health threat in six years, the U.S. Centers for Disease Control and Prevention said it had determined that 2.8 million antibiotic resistant infections occur each year, killing 35,000 people.

A 2013 CDC study estimated that 2 million Americans were infected by superbugs each year, leading to at least 23,000 deaths.”The 2013 report propelled the nation toward critical action and investments against antibiotic resistance. Today’s report demonstrates notable progress, yet the threat is still real,” Dr. Robert Redfield, the CDC’s director, said in a statement.

Global health officials have repeatedly warned about the rise of bacteria and other microbes that are resistant to most available drugs, raising the specter of untreatable infectious diseases that could spread rapidly.

Drug resistance is driven by the misuse and overuse of antibiotics and other antimicrobials, which encourages bacteria to evolve to survive by finding new ways to beat the medicines.

The CDC said that 2019’s higher numbers were the result of new and better data sources, not a rise in fatalities, and that in fact prevention efforts had decreased deaths from the hard-to-kill germs by 18%.

A spokeswoman for the nonprofit Natural Resources Defense Council, however, called even the CDC’s new estimate far too low, saying that a recent Washington University study put the death toll at more than 160,000.

“There is no doubt that drug-resistant infections are on the rise. While CDC’s estimates have improved, they remain conservative,” said Avinash Kar, a senior NRDC attorney.

“Solving antibiotic resistance will require ending the rampant overuse of these drugs in livestock. Until then, these lifesaving drugs will increasingly fail when sick people need them—and, as CDC recognized, ‘everyone is at risk,’” Kar said.

The NRDC said nearly two-thirds of antibiotics important for human medicine are sold for use in livestock, distributed en masse in feed or water, often to animals that are not sick.

The CDC said the antibiotic resistance “threat list” now contained 18 germs, including two more that were considered urgent: drug-resistant Candida auris and carbapenem-resistant Acinetobacter.

Three urgent threats were identified in the 2013 report: carbapenem-resistant Enterobacteriaceae or CRE, Neisseria gonorrhoeae, and Clostridioides difficile.