Synthetic Biologics Inc said its experimental treatment designed to reduce antibiotic-resistant "superbug" infections - notably life-threatening C. difficile - outperformed a placebo in a trial.
The company's oral enzyme, ribaxamase, met the main goal of significantly reducing Clostridium difficile infection, the most common cause of hospital-associated infectious diarrhea.
Ribaxamase, tested against a placebo in a 412-patient mid-stage study, is being developed to protect trillions of "good" bacteria living in the digestive system from the unintended effects of intravenous antibiotic use.
These bacteria are believed to play a role in everything from obesity to depression.
Seven cases of C. difficile infection were reported in the placebo group, compared to two in the ribaxamase group, a preliminary analysis showed.
As the antibiotics typically used to treat C. difficile kill good bacteria, it becomes more difficult for the body to fend off the C. difficile germ, creating a vicious cycle.
C. difficile is most often spread through hospital surfaces and human contact and typically affects the elderly.
Switzerland's Nestle SA, the world's largest food company, said in September it was looking into so-called microbiome therapy, a concept that includes faecal transplants, to cure C. difficile.
This therapy can cure patients by replenishing the good bacteria in their gut by transplanting bacteria from a healthy person's stool, delivered through a nasal or rectal tube.
Antibiotic-resistant infections are a grave threat to public health. A Reuters investigation has found that infection-related deaths are going uncounted, hindering the ability of the United States to fight the scourge.
Synthetic Biologics' shares were up 12 percent at 99 cents in premarket trading.
(Reporting by Natalie Grover in Bengaluru; Editing by Ted Kerr)