A deadly strain of hard-to-treat bacteria is spreading in U.S. health facilities, posing a particular risk to the nation's most vulnerable patients, authorities said in a report on Tuesday.
Health officials said the bacteria has proved stubbornly resistant to treatment with antibiotics, making some infections impossible to cure.
Up to half of all patients who get blood stream infections from the bacteria die, health officials said.
The report about the lethal bacteria -- carbapenem-resistant enterobacteriaceae (CRE) -- was issued by Vital Signs, a publication of the Centers for Disease Control and Prevention.
"CRE are nightmare bacteria. Our strongest antibiotics don't work, and patients are left with potentially untreatable infections," said CDC Director Tom Frieden.
Enterobacteriaceae are a family of more than 70 bacteria, including E. coli, that normally live in the digestive system.
Some of the bacteria have become resistant over the years to antibiotics known as carbapenems -- often seen as the medication of last resort when treating bacteria.