CHICAGO — A family of drug-resistant bacteria that experts say kills up to 50 percent of people infected is spreading, prompting doctors and public health officials to step up efforts to protect patients.
Infections caused by these germs — called carbapenem-resistant enterobacteriaceae, or CRE — are still rare, but they are difficult and sometimes impossible to treat. Carbapenems are antibiotics used as a last-resort treatment for seriously ill people.
No one knows the exact number of CRE infections or deaths nationwide, though the Centers for Disease Control and Prevention are working on a report that would compile those statistics for the first time.
But the CDC says an increasing percentage of germs in the enterobacteriaceae family are becoming resistant to carbapenems. A decade ago, 1 percent of these bacteria were resistant; now 4 percent are. One type has increased from 2 percent to 10 percent. In all, more than 70 kinds of bacteria have developed carbapenem resistance.
One type recently identified in Chicago is called carbapenem-resistant Klebsiella, first reported in the U.S. in 2001.
It didn't exist in Chicago before 2007, experts say, but by 2011 it had emerged and spread quickly. A state health department survey conducted that year found that every hospital in suburban Cook County and 80 percent of hospitals in Chicago had identified at least one patient infected with it.
So far, CRE have been identified only in patients in hospitals, nursing homes and other long-term, acute-care hospitals, but health professionals say the bacteria could pose a threat to public health if it spreads into the general community.
During an outbreak of one type of CRE in 2011 at the National Institutes of Health's Clinical Center in Bethesda, Md., six patients died from the infection and five died from underlying disease while infected.
"CRE are nightmare bacteria," Dr. Tom Frieden, director of the CDC, said recently. "They pose a triple threat. First, they're resistant to all or nearly all antibiotics. Even some of our last-resort drugs. Second, they have high mortality rates. They kill up to half of people who get serious infections with them. And third, they can spread their resistance to other bacteria."
For example, carbapenem-resistant Klebsiella could spread genes that interfere with the body's ability to respond to antibiotics to E. coli bacteria, which are the most common cause of urinary tract infections in healthy people.
Information about the number of CRE infections is scarce in part because only six states require health facilities to report cases — Tennessee, Oregon, Minnesota, Colorado, Wisconsin and North Dakota. The CDC said its surveillance systems pick up the percentage of pathogens resistant to particular drugs, not the number of cases or deaths.
Wisconsin, which required hospitals to report CRE infections starting in December 2011, has since identified 25 cases in 17 of the state's 137 hospitals and long-term, acute-care facilities. Nineteen involved a carbapenem-resistant Klebsiella species; the others were carbapenem-resistant E. coli.
The CDC has tracked CRE from a single health care facility in one state in 2001 to health care facilities in at least 42 states. In some of those places, these bacteria have become relatively commonplace, Frieden said.
CRE are spread by unclean hands, but medical devices such as ventilators or catheters increase the risk of life-threatening infection because they can introduce new bacteria into the bloodstream.
The CDC last year recommended that facilities promote proper hand washing by health care workers, remove medical devices such as catheters as soon as possible, isolate patients who are infected or carry the bacteria and make sure that health workers are using protective gloves and gowns when touching patients with CRE, among other things.
Frieden urged health facilities to employ a "detect and protect" strategy, which involves identifying the presence of the organism and protecting other patients to prevent its spread.
Frieden said health facilities have been successful in controlling CRE by using CDC-recommended prevention and control techniques.
But Betsy McCaughey, chairman and founder of the Committee to Reduce Infection Deaths, a patient advocacy group, said CDC officials haven't gone far enough. She wants the CDC to push for mandatory CRE screenings at hospitals in all states and require public reporting of data.
"If patients are going into the hospital for something elective like a hip replacement, they would want to avoid going into a hospital that is battling carbapenem-resistant bacteria," she said.
Health authorities advise consumers to take simple precautions to protect themselves, such as frequently washing their hands properly.