The bacteria, known as Carbapenem-Resistant Enterobacteriaceae, or CRE, are named for their ability to fight off carbapenem antibiotics -- the last line of defense in the medical toolbox. And so far, they've emerged almost exclusively in health care facilities, picking off the weakest of patients.

The bacteria made headlines this summer after a CRE strain of Klebsiella pneumoniae battered the National Institutes of Health Clinical Center outside Washington, D.C. Seven died, including a 16-year-old boy. (Hospitals don't reveal victims' names in keeping with medical privacy rules.) But that case was neither the first nor the worst of the CRE attacks.