Government officials want the nation's health care providers to step up efforts to halt the spread of a drug-resistant "nightmare bacteria" that attacks the bloodstream and kills up to half of patients who become infected. In the first half of 2012, nearly 200 hospitals and acute care facilities treated at least one patient for the lethal "superbug" known as CRE, according to new data from the U.S. Centers for Disease Control and Prevention. Dr. Tom Frieden, director of the CDC, called CRE a "nightmare bacteria" because of its high mortality rate, its resistance to nearly all antibiotics and its ability to spread its drug resistance to other bacteria that otherwise would be vulnerable to vaccines.