WebMD Medical News
Louise Chang, MD
Sept.16, 2009 (San Francisco) -- Researchers are developing a novel
antibiotic that they hope can help turn the tide in the epidemic of the nasty
bug Clostridium difficile, or C. diff.
Dubbed NVB302, the drug is the first in a new class of antibiotics called
Type B lantibiotics to undergo testing against C. diff.
NVB302 successfully killed C. diff in test tube studies and prolonged
survival in hamsters infected with the bacterium. Novacta Biosystems, the
company developing the drug, hopes to start human studies within a year, says
Michael J. Dawson, MD, chief scientific officer.
The potentially dangerous diarrhea bug causes several hundred thousand human
infections and several thousand deaths each year in the United States,
according to the CDC.
In recent years, the number and severity of these infections has been on the
rise, says Curtis Donskey, MD, an infectious diseases specialist at Case
Western Reserve University in Cleveland.
“Cases have tripled in the last few years,” he tells WebMD.
Most cases of C. diff occur in people taking so-called broad spectrum
antibiotics that kill many different types of pathogens.
Spores enter the body through the mouth, which is the entryway for the
gastrointestinal tract. The broad spectrum antibiotics kill “good” bacteria in
the gut that keep C. diff at bay.
The resulting overgrowth of the C. diff bacteria in the colon, or
large intestine, can cause diarrhea, which is often severe and accompanied by
intestinal inflammation known as colitis.
Other more selective antibiotics such as Vancocin and Flagyl are typically
used to treat the infection, but many patients still suffer recurrences, says
Sjoerd Wadman, PhD, director of therapeutic products at Novacta.
These drugs work in about 75% of patients, he says. “But after seemingly
successful initial treatment, symptoms come back in some 20% to 25% of patients
10 to 30 days later,” he tells WebMD.
Researchers don’t fully understand why recurrences occur, but they believe
that even these "selective" antibiotics sometimes kill off the "good" pathogens
in the gut, Wadman says.
“New therapeutic approaches are urgently needed," he says.
That’s where NVB302, which is given in tablet form, comes in. In test tube
studies, "it targeted C. diff very selectively, allowing normal gut
[bacteria] to recover," Wadman says.
In the animal studies, the researchers infected hamsters with C.
diff. They also gave them the antibiotic clindamycin, which disturbed the
normal gut flora and allowed C. diff to grow.
If the animals aren’t treated further, they will die within 72 hours, Dawson
says. But they lived much longer when given NVB302, he says.
The research was presented at the annual Interscience Conference on
Antimicrobial Agents and Chemotherapy.
Now the company is conducting safety studies in healthy animals, a step
required by the FDA before human testing can proceed.
One of the big advantages of the new drug is that the studies showed it is
not significantly absorbed into the bloodstream after being given orally, says
Karen Bush, PhD, an expert specializing in the development of new products for
infectious diseases at Indiana University, Bloomington.
“This means it’s less likely to affect the normal [healthy] bacteria [than
other antibiotics],” she tells WebMD. Bush was not involved with the work.
SOURCES:49th Interscience Conference on Antimicrobial Agents and Chemotherapy, San
Francisco, Sept. 12-15, 2009.Michael J. Dawson, MD, chief scientific officer, Novacta Biosystems, Welwyn
Garden City, U.K.Curtis Donskey, MD, Case Western Reserve University, Cleveland.Sjoerd Wadman, PhD, director of therapeutic products, Novacta Biosystems,
Welwyn Garden City, U.K.Karen Bush, PhD, Indiana University, Bloomington.
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