Antibodies Keep C. Diff at Bay

Giving two monoclonal antibodies along with antibiotics cut recurrence of Clostridium difficile (c. diff) infection significantly.

When a single injection of the two antibodies against c. difficile toxins was given, 7 percent of patients had their infection return within the next 84 days.  In comparison, patients who got a placebo shot, had a 25 percent recurrence rate.

The antibodies were even more effective in preventing recurrence in patients who had had more than one episode of c. diff.

In a randomized clinical trial, half of the patients received an injection of monoclonal antibodies against the c. difficile toxins CDA1 and CDB1 as well as antibiotics metronidazole or vancomycin.  The other half got antibiotics, but a placebo injection.

In the 84 days after treatment:

• 7 percent of those receiving antibodies had infection recur compared to 25 percent who got placebo.
• Among patients who had more than one episode of c. difficile infection, 7 percent on antibody treatment had a recurrence compared to 38 percent of those who weren’t.
• For patients with the serious, antibiotic resistant NAP1/027 strain, recurrence rates were 8 percent in the treated group and 32 percent for controls.

There didn’t appear to be any safety issues with the monoclonal antibodies.  During the follow-up period, there were 18 serious adverse effects in the antibody group and 28 in the control group.  In the two hours after the injection 15 treated patients and 10 placebo patients had a mild to moderate side effect, mostly headaches.

However, the study authors point out that a larger trial is necessary to completely rule out serious side effects and confirm the findings.

Clostridium difficile bacteria cause a severe infection in the colon with diarrhea and inflammation.  Although mild cases respond to antibiotics, about 15 to 30 percent of patients will have infection return.  A more virulent strain has emerged in the past few years that resists routine antibiotics.  Antibiotics can create a favorable environment for the growth of c. difficile bacteria in the intestinal tract by killing helpful bacteria normally living there.

Previously, most cases were in patients in hospitals, but growing numbers of people who are not hospitalized are acquiring the disease.

Reporting their findings in the New England Journal of Medicine, Israel Lowy, MD, PhD and his colleagues concluded,

The addition of monoclonal antibodies against C. difficile toxins to antibiotic agents significantly reduced the recurrence of C. difficile infection.

SOURCE: Lowy et al., New England Journal of Medicine,Volume 362, Number 3, pp. 197-205, January 21, 2010.