For six months in 2011, doctors at the nation's premier medical research and treatment center -- the National Institutes of Health -- were seeking the source of a killer -- in their own facility.
Patients in the 243-bed facility were contracting an infectious organism that medical investigators ultimately traced to a patient from New York City, who was carrying a multi-drug-resistant strain of Klebsiella pneumoniae, considered among the most lethal of hospital-acquired bacteria.
The New York patient went to the NIH facility in Bethesda, Md., to participate in a clinical trial but inadvertently caused 17 patients to be colonized with the resistant strain. Eleven died: six directly from the infection, five from their underlying disease while infected, NIH officials say.
Now, a new study in the journal Infection Control and Hospital Epidemiology finds that the family of microbes to which the resistant Klebsiella belong has been quietly gaining multi-drug resistance for years.
The dilemma: Doctors have run out of choices to treat the lethal strains because they resist the class of antibiotics considered the drugs of last resort, the carbapenems.
Because of their resistance, these superbugs are broadly referred to as carbapenem-resistant enterobacteria, or CRE for short.
There are no new antibiotics of greater strength in the immediate future, leading some experts to ponder whether the emboldened microbes may have finally won.
"These infections are very difficult to contain and very difficult to treat," said Nikolay Braykov, an author of the new research and a senior analyst at the Center for Disease Dynamics, Economics and Policy in Washington.
Enterobacteria are the normally harmless colonies that reside in the human large intestine. When overexposed to antibiotics, they develop the genetic capacity to repel antibiotics.
Among the mightiest of hospital superbugs, they can be transmitted from the unwashed hands of health care workers or items -- including bed rails -- in hospital rooms, spreading like wildfire.
CRE infections are deadlier than the bacteria MRSA and Clostridium difficile, Braykov said.
People most at risk are those under treatment in intensive care units or residents of nursing homes where outbreaks have been occurring with increasing frequency, the study's authors say.
The Centers for Disease Control and Prevention estimate CRE kills up to 40 percent of affected patients. There is evidence, according to CDC data, that CRE outbreaks have occurred in 41 states.
In 2002, according to the research, only 0.1 percent of infectious disease samples diagnosed in nearly 300 clinical laboratories nationwide were positive for CRE. By 2010, the total had reached 4.5 percent -- and the cases continue to mount, the researchers say.
Public health experts do not believe CRE infections are as widespread as MRSA or C. diff, but they have no data to support the claim because states, including New York, which monitors hospital infections, do not track CRE.
"Individual cases are not reportable," said Peter Constantakes, a spokesman for the New York State Department of Health. "Sometimes with outbreaks we do get reports. But we've asked hospitals to voluntarily start doing it," he said.
The first incidence of the new deadly strain was reported in 2001 in North Carolina. But Braykov's study indicated the upsurge in CRE cases started about six years ago when an outbreak occurred in Brooklyn and then spread to nearby hospitals in Manhattan. Other incidents quickly followed throughout the Mid-Atlantic region.
"It's a deep and serious problem," said Dr. Bruce Farber, chief of infectious diseases at North Shore University Hospital in Manhasset.
"They [the resistant strains] originally appeared in Asia, then spread worldwide. It's a reflection of the fact that we need new antibiotics," Farber said.
Farber attributes CRE's mounting spread to Darwinian principles. The bacteria, he said, evolve quickly and possess the genetic machinery to not only adapt to their chemical environment, but to overcome it.
Betsy McCaughey, former New York lieutenant governor and executive director of the Committee to Reduce Infection Deaths, considers CRE a chilling prospect for health care.
"We are truly moving into an era of no cures -- the post-antibiotic era," she said. "We should be tracking these bugs, tracking them from nursing homes to hospitals. We need to track them because we can't treat them and they are alarmingly present right here in New York."