There’s more evidence that untreatable or tough-to-treat infections from a rare but deadly superbug are on the rise in U.S. hospitals, ratcheting up concerns about stopping the spread before it gets worse, health officials said Tuesday.

Last year, about 4 percent of U.S. acute-care hospitals and 18 percent of long-term acute care hospitals reported at least one case of dangerous CRE bacteria -- Carbapenem-resistant enterobacteriaceae -- germs resistant to most last-resort antibiotics.

That’s according to new figures released by the Centers for Disease Control and Prevention, which analyzed data from about 3,900 U.S. hospitals in the first six months of 2012.

"CRE are nightmare bacteria," CDC Director Dr. Tom Frieden told reporters.

Figures may show that CRE are still rare, but analysis from three different data pools revealed a big jump in the infections during the past decade. The percentage of certain bacteria reported to be resistant to carbapenem antibiotics -- often the drugs of last resort -- climbed from 1.2 percent in 2001 to 4.2 percent in 2011, a spike of about 250 percent.

“The message that we’re trying to send is there’s an opportunity here,” the CDC’s Dr. Arjun Srinivasan, associate director for healthcare-associated prevention programs said in an interview before Tuesday's press conference. “It’s an uncommon issue, but it’s concerning. There’s an opportunity to act while it’s still uncommon.”

CREs increased most for the worrisome Klebsiella pneumoniae, jumping from 1.6 percent to 10.4 percent between 2001 and 2011, a rise of 550 percent. That’s the bug that made headlines last summer after reports that it was part of an outbreak that swept through the National Institutes of Health Clinical Center near Washington, D.C., killing seven people, including a 16-year-old boy.

CDC relied on CRE data collected from the National Nosocomial Infection Surveillance System, or NNIS, and its successor, the National Healthcare Safety Network, or NHSN. More data came from another source called the Surveillance Network-USA, known as TSN.

CREs are part of a family of drug-resistant germs that have shown up in growing numbers of U.S. health care settings. They’re named for their ability to fight off carbapenem antibiotics, which have been the big gun drugs used to treat serious infections. CRE infections typically show up in people who’ve been hospitalized frequently, who have been taking antibiotics and who may require devices such as ventilators or catheters.

They often present as hard-to-treat bloodstream or urinary tract infections.

CRE infections tied to Klebsiella now have been detected in 42 U.S. states and Puerto Rico, the CDC reports. That's particularly worrisome because the mortality rate for CRE bloodstream infections can be as high as 50 percent and CRE infections can spread like wildfire through a hospital.

CDC

CDC microbiologist Kitty Anderson holds up a 96-well plate used to test the ability of bacteria to grow in the presence of antibiotics. CDC officials report that Carbapenem-resistant enterobacteriaceae are on the rise in U.S. hospitals.

No one knows exactly how many cases there have been in the U.S. or how many deaths may be tied to CREs, Srinivasan said.

CDC has launched an all-out campaign -- a "detect and protect" strategy to urge hospitals and other health care facilities to be on guard for CREs. The agency issued a health alert last month warning that the number of unusual forms of CRE has nearly doubled since last July. That includes the notorious NDM bug -- New Delhi metallo-beta-lactamase -- which produces an enzyme that renders antibiotics virtually useless.

Health care providers should be alert for evidence of CRE in their facilities, CDC says, and act promptly to detect and contain the bug. Patients exposed to the germ should be kept together, away from others. Hospital staff should be vigilant about hand hygiene and exposing patients to potentially contaminated materials. Some states and some sites have better systems in place to catch CREs, including places such as Colorado and Florida, which have had outbreaks and grappled with the problem of stopping them.

“The actions right now are uneven,” Srinivasan said.

Patients worried about catching a CRE infection can take certain precautions, too, he suggested. Risk may be higher in people who are hospitalized frequently or who are transferred from one type of hospital to another. For instance, someone who suffers a stroke may be treated at an acute-care hospital, but then transferred for longer-term critical care at another site.

Patients or family members should ask about the risk of CRE, especially in people who require ventilators or catheters or those who show signs of infection, such as a fever. Check with the staff about the steps they take to prevent hospital-acquired infections, Srinivasan said.

“Ask: What are you doing to keep me safe from CRE?” he suggested.

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CDC

In the U.S. today, the most common type of highly drug-resistant germs known as CREs are the Klebsiella pneumonia bacteria like those shown here. Nearly untreatable, they're being detected in a growing number of health care settings.

A sharp jump in the number of rare but potentially deadly types of a superbug resistant to nearly all last-resort antibiotics has prompted government health officials to renew warnings for U.S. hospitals, nursing homes and other health care settings.

The move comes just as researchers in Israel are reporting that people who carry dangerous CRE -- Carbapenem-resistant enterobacteriaceae -- can take more than a year before they test negative for the bacteria, making it more difficult to control and raising the risk of wider spread.

Reports of unusual forms of CRE have nearly doubled in the U.S., the Centers for Disease Control and Prevention reported this month. Of 37 cases of rare forms of CRE, including the alarming NDM  -- New Delhi metallo-beta-lactamase -- 15 have been reported since last July.

“This increase highlights the need for U.S. health care providers to act aggressively to prevent the emergence and spread of these unusual CRE organisms,” the CDC said in a health advisory.

CREs are part of a family of drug-resistant germs that have shown up in growing numbers of U.S. health care settings. They’re named for their ability to elude carbapenem antibiotics, the big guns in the medical arsenal. They usually strike people who are already ill and require devices such as ventilators or catheters or who have been taking antibiotics for a long time. But they can infect any patient.

Twenty-nine of the unusual CRE cases have been NDM, up from the first case detected in the U.S. in 2010, said the CDC's Dr. Alex Kallen, a medical epidemiologist and outbreak response coordinator in the agency’s Healthcare Quality Promotion division. It's especially worrying because it confers resistance to multiple drugs and is easily transmitted to other types of bacteria.

The others were even rarer types of CRE, including VIMs, IMPs and OXA-48s, all of which produce enzymes that render most antibiotics virtually useless.

The agency called for stricter isolation and hygiene precautions, increased screening of patients potentially colonized with CRE and better communication within and between hospitals and other health care settings where the bugs can become intractable -- and deadly. CRE infections have a mortality rate of up to 40 percent, much higher than other health care infections, such as those caused by MRSA or C. difficile.

“Our main objective is to slow or stop the spread in places where we can identify them,” said Kallen. “Right now, the therapeutic options are very limited.”

Health officials have been worried about them for more than a decade, particularly the KPCs, or carbapenemase-producing Klebsiella pneumonia, which have now been reported in 42 U.S. states and Puerto Rico, the CDC reports.

Nine states have reported NDMs and at least two have reported other rare forms that also block antibiotic effectiveness, including those known as VIMs, or Verona integron-encoded metallo-beta-lactamase, and IMPs.  So far, they’ve been associated mostly with people who’ve been hospitalized in countries outside the U.S.

The bugs were in the news last summer after reports of a CRE strain of Klebsiella pneumoniae roared through the National Institutes of Health Clinical Center near Washington, D.C., killing seven people, including a 16-year-old boy.

In Colorado last summer, NDM-producing CRE was detected in eight patients, the largest outbreak in the U.S. to date, according to a CDC report this month. It was found largely because the University of Colorado Hospital already has stringent surveillance protocols in place, said Dr. Michelle Barron, director of infection control and prevention. Since then, the hospital has probably tested 500 or 600 patients with unusual resistance patterns, she told NBC News.  

None of the eight patients in the original outbreak died. The evidence showed that patients who were colonized with the germs, but not actually sick, contributed to the spread.

That’s a point underscored by the study by Israeli doctors published Wednesday in the American Journal of Infection Control. They studied medical records of adult patients hospitalized between January 2009 and December 2010 at Shaare Zedek Medical Center, a 700-bed, university-affiliated hospital in Jerusalem.

In 97 patients with positive CRE cultures, it took a mean time of 387 days to log a negative test -- and nearly 40 percent remained positive after a year, according to Dr. Amon Yinnon, one of the study authors.

“The major concern is that an undiagnosed carrier may be admitted to hospital for totally unrelated reasons, and subsequently and unwittingly pass his CRE to other patients,” Yinnon said in an email to NBC News.

Patients who were hospitalized repeatedly were at higher risk of remaining colonized with CRE, the study found.

CDC officials hope to increase awareness of the growing problem among the general public as well as the health care providers before it gets out of control.

“I can’t predict the future, of course, but there is a concern that we can see more of these as they spread,” Kallen said. “This can become a community bug.”

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By The Associated Press

A deadly germ untreatable by most antibiotics has killed a seventh person at the National Institutes of Health Clinical Center in Maryland.

The Washington Post reported the death Friday. NIH officials told the paper that the boy from Minnesota died Sept. 7. NIH says the boy arrived at the research hospital in Bethesda in April and was being treated for complications from a bone marrow transplant when he contracted the bug.

He was the 19th patient at the hospital to contract an antibiotic-resistant strain of KPC, or Klebsiella pneumoniae. The outbreak stemmed from a single patient carrying the superbug who arrived at the hospital last summer.

The paper reported the Minnesota boy's case marked the first new infection of this superbug at NIH since January.

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