648,000 Got Hospital-Related Infections in 2011
Specific source of dangerous germs still unclear in about half of cases
C. difficile can cause deadly diarrhea and results from antibiotic overuse. The germ infests a person's colon after antibiotics have wiped out the healthy bacteria that normally resides in their gut.
"This is not just the nuisance diarrhea it used to be 12 years ago," Bell said, noting that the germ produces a toxin that has grown more powerful over time. "That toxin chews up the colon to such an extent that people have to have their colons removed to save their lives."
These other germs most commonly spread in hospitals all have strains that are antibiotic resistant:
Staphylococcus aureus, including MRSA (11 percent)
Klebsiella (10 percent)
E. coli (9 percent)
Enterococcus (9 percent)
The fight to halt the spread of antibiotic-resistant germs continues to be a top priority for U.S. hospitals, said Nancy Foster, vice president of quality and patient safety policy for the American Hospital Association (AHA).
"It's a very complex and challenging clinical area, but one that doctors and nurses and pharmacists are passionate about getting their hands around because we can see how devastating it can be for patients," Foster said.
The new study resulted from the CDC's multistate survey of infections associated with health care. The survey used 2011 data from 183 U.S. hospitals to estimate the burden of a wide range of infections in hospital patients across the country.
Researchers already are taking steps to track down the unknown causes of hospital infections, CDC's Bell said.
For example, many of the pneumonia cases not caused by ventilation could occur due to aspiration, with the patient breathing in germs in their own saliva or regurgitation.
"If we find that a lot of this is aspiration, that's a big deal," he said, noting that cutting back on the use of sedatives could cut back on aspiration and, as a result, the number of pneumonia cases. "That sort of thing we can tackle with a coordinated effort."
Hospitals are investigating other sources of infection, including the spread of disease back and forth between hospitals and care facilities, AHA's Foster said.