WEDNESDAY, Feb. 2 (HealthDay News) -- Late-stage clinical trials
of a new antibiotic for the increasingly common intestinal
Clostridium difficile, which is especially lethal to the elderly, suggest it prevents recurrence far better than currently used medications.
Researchers tested the new drug, fidaxomicin, against
vancomycin, a powerful drug often prescribed to
C. difficile patients. These cases often involve virulent
diarrhea and colon inflammation that proves fatal to an estimated
5,000 Americans each year, according to federal statistics.
People over age 65, especially those in hospitals and nursing
homes, are more vulnerable to the infection, which experts estimate
strikes up to 3 million Americans annually, many of whom have taken
broad-spectrum antibiotics to treat other illnesses.
Among the 629 patients studied, fidaxomicin was associated with
a 45 percent lower rate of recurrence than vancomycin, which
researchers said was due to fidaxomicin's ability to precisely
C. difficile bacteria in the gut. Vancomycin has a similar
clinical cure rate, but it kills more "good" intestinal bacteria
bugs that help keep
C. difficile at bay, explained study co-author Dr. Sherwood
"It's virtually impossible to beat vancomycin as a cure, but [using fidaxomicin] we could beat it with recurrence," said Gorbach, professor of medicine, immunology, molecular biology and microbiology at Tufts University School of Medicine in Boston.
"Fidaxomicin does kill the bug, but in terms of recurrence, it doesn't disturb the normal balance of flora in the intestines," he said. "This drug should actually save lives."
The study was funded by Optimer Pharmaceuticals, which is
developing fidaxomicin, and is published in the Feb. 3 issue of the
New England Journal of Medicine.
While vancomycin is often used as a last-resort antibiotic to
treat drug-resistant infections -- an emerging public health menace
-- fidaxomicin was not developed because
C. difficile is becoming resistant to vancomycin or
metronidazole, the standard drugs used for milder cases, Gorbach
"The reason for failures is not resistance," he said. "Vancomycin and fidaxomicin both have a 10 percent failure rate. It may be that the spores don't get killed very easily and allow for this disease to continue. It's being called the hospital 'superbug' now."
Enrolled at 52 sites in the United States and 15 in Canada,
participants in the phase 3 clinical trial were classified
according to whether their current
C. difficile infection was the first or second episode.
Patients took either fidaxomicin (200 mg twice daily) or vancomycin
(125 mg four times daily) orally for 10 days and were followed
afterward to determine if their diarrhea had resolved.
A recurrence was defined by the reappearance of more than three
diarrheal stools per 24-hour period within four weeks after
completion of the drug therapy.
Not only was the recovery time faster among those who took
fidaxomicin, but nearly 75 percent recovered without a recurrence,
compared to 64.1 percent for the vancomycin patients.
"The people who've had this disease generally say it's the worst disease they've ever had," Gorbach said. "Because [fidaxomicin] decreases recurrences by 45 percent -- and recurrences usually require another hospital stay -- it will actually save money."
Dr. Clifford McDonald, chief of the prevention and response
branch of the U.S. Centers for Disease Control and Prevention's
division of healthcare quality, said the lower recurrence rate of
C. difficile associated with fidaxomicin could also lower the
transmission rate among patients.
"This does seem like a pretty strong result scientifically," McDonald said. "Hopefully we'll see more antibiotics like this."
McDonald also pointed out that fecal transplants -- a novel
C. difficile that helps restore beneficial intestinal
bacteria levels by infusing patients with a stool slurry from a
healthy donor -- goes hand-in-hand with efforts to develop
antibiotics that destroy fewer of these bacteria.
"Antibiotics do collateral damage. They're not safe to bacteria that have been good to us all along," McDonald said. "I think there's a growing realization that we're not just mammals, but mammals with bacteria on us, and the two co-exist in health."
The U.S. Food and Drug Administration is expected by the end of
May to decide if fidaxomicin will go to market later this year,
Gorbach said. He and other team members asked for fast track
consideration of the drug, saying it meets an unmet need and should
be given rapid deliberation.
Find out more about
C.difficile at the
U.S. National Library of Medicine.
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