C. difficile is one of the most common infections found in hospitals and long-term-care facilities, Health Canada says. (CBC)

Combining two therapies may help cut recurrence of C. difficile, a potentially deadly bacterial infection, early-stage research suggests.

C. difficile, which is widespread in the environment, has been at the centre of various hospital outbreaks. The bacteria infect the gastrointestinal tract, and can cause severe diarrhea and critical illness.

During a six-month period in 2006 in Quebec, a study concluded that a virulent hospital strain of C. difficile known as NAP-1 was indirectly responsible for 108 deaths. After the outbreak, Quebec became the first province to require hospitals to publicly report the number of cases they faced.

But giving two monoclonal antibodies designed to remove two toxins produced by the bacteria helped to prevent recurrence of the infections, researchers reported in Thursday's New England Journal of Medicine.

The Phase 2 trial randomly assigned 200 patients with C. difficile infections the U.S. and Canada to standard antibiotic treatments and injections of two monoclonal antibodies or a saline placebo. Participants were followed for 84 days.

Among those who received the antibodies, seven per cent suffered a recurrence, compared to 25 per cent in the placebo group, the researchers found.

Among 44 patients with the NAP-1 strain, eight per cent who were given the antibodies had a relapse, compared to 32 per cent in the placebo group.

"We're really hopeful that this is a new therapy and a new option for patients," said study author Dr. Donna Ambrosino of the University of Massachusetts Medical School in Boston.

Larger studies are needed before the antibodies could be licensed for patients, she said.

Breaking cycle of infection

Monoclonal antibodies have also been developed against some cancers, rheumatoid arthritis and multiple sclerosis. C. difficile is the second time this type of treatment has been used for an infectious disease, after respiratory syncytial virus in infants, Ambrosino said.

"These novel approaches to breaking the cycle of C. difficile infection, along with continued attention to appropriate antibiotic use and infection prevention and control, offer hope in the battle against this increasingly prevalent and difficult-to-manage disease," Dr. Lorraine Kyne, a geriatric medicine specialist of University College, Dublin, concluded in a journal editorial accompanying the study.

The monoclonal antibodies were developed by the University of Massachusetts's non-profit MassBiologics arm and Medarex, a subsidiary of Bristol-Myers Squibb. Rights have been licensed to Merck, which would be responsible for performing the larger safety studies needed for regulatory approval to market the treatments.

With files from The Canadian Press