Deadly diarrhea disease C. difficile infects almost 500,000 in U.S. each year

More than 80% fo C. difficile-associated deaths involve people 65 or older, study finds

Clostridium difficile, a bacterium that causes swelling of the colon and potentially deadly bouts of diarrhea, infects almost half a million people each year and contributes to the deaths of 29,000, according to new research.

In a paper published Wednesday in the New England Journal of Medicine, researchers reported that C. difficile-associated deaths had more than doubled since 2007 and that more than 80% of those fatalities involved people 65 or older.

The bacterium most commonly infects patients in healthcare settings -- inpatient and outpatient -- after they have been prescribed broad-spectrum antibiotics. These drugs not only kill harmful germs, but they also kill beneficial bacteria that occupy the human gut and protect against infection.

As a result, the patients are highly vulnerable to acquiring an infection from other patients, contaminated medical instruments, or from contaminated surfaces.

"C. difficile infections cause immense suffering and death for thousands of Americans each year," U.S. Centers for Disease Control and Prevention Director Thomas Frieden said in a statement. "These infections can be prevented by improving antibiotic prescribing and by improving infection control in the healthcare system."

As an example, the CDC said that more than half of the antibiotics prescribed for upper respiratory infections in outpatient care settings were unnecessary.

The study's estimates were based on observations at 10 CDC surveillance sites in 2011. Extrapolating from those cases, the authors calculated that the bacterium caused about 453,000 infections that year, with 29,000 associated deaths.

"C. difficile has become the most common cause of healthcare-associated infections in U.S. hospitals, and the excess healthcare costs related to C. difficile infection are estimated to be as much as $4.8 billion for acute care facilities alone," wrote lead study author Dr. Fernanda Lessa, a CDC epidemiologist.

People 65 or older, whites and females had the highest rates of incidence, according to Lessa and her colleagues.

They also found that 1 out of every 5 patients with healthcare-associated C. difficile infection experienced a recurrence of the infection, while 1 out of 9 patients aged 65 or older died within 30 days of diagnosis.

Frieden and other CDC officials say that a nationwide initiative to combat C. difficile had the potential to cut infections in half.

"CDC hopes to ramp up prevention of this deadly infection by supporting State Antibiotic Resistance Prevention Programs in all 50 states," Frieden said.

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