Merck has announced two Phase 3 clinical studies for an investigational antitoxin for prevention of Clostridium difficile (C. difficile) infection recurrence found the treatment effectively reduced infection recurrence over 12 weeks when paired with standard antibiotics.

The drug would be the first and only to prevent C. difficile recurrence, and the company now plans to  submit new drug applications asking for regulatory approval of bezlotoxumab in the U.S., EU and Canada this year.

"Results of these studies showed that a single, one-time infusion of the antitoxin bezlotoxumab given with standard of care C. difficile antibiotic treatment significantly reduced the recurrence of C. difficile infection compared to standard of care alone, and demonstrated this benefit over a 12-week period," said Mark Wilcox, Leeds Teaching Hospitals and University of Leeds, U.K., and a lead investigator for the studies. "These results were also demonstrated in patient subgroups known to be at high risk for C. difficile recurrence."

Bezlotoxumab is a "selective, fully-human, monoclonal antibody" that neutralizes C. difficile toxin B, which can damage the gut wall and cause the inflammation linked to symptoms of the infection.

"Recurrence is a major challenge with C. difficile infection, and novel approaches are needed to help prevent the cycle of C. difficile recurrence," said Dale Gerding, professor of medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Ill., and a lead investigator for the studies.

Incidences of C. difficile have risen dramatically over the past few 20 years, and is believed to have caused almost half a million infections in the U.S. in 2011. The infection most often effects patients staying in healthcare setting who recently took certain antibiotics or medications. Recurrence will occur in about one in four C. difficile patients after the initial episode, and 40 percent of these patients will experience further problems.

The findings were presented at the Interscience Conference of Antimicrobial Agents and Chemotherapy (ICAAC) and International Congress of Chemotherapy and Infection (ICC) joint meeting