Safety and efficacy of nontoxigenic C. difficile spores in preventing recurrent CDI

Lead Author: Dr. Dale Gerding

We have written and spoken often on the efficacy of fecal transplants in treating recurrent C. difficile infections. Wouldn't it be great if there was a way to prevent recurrent CDI in the first place? What if "good" C. difficile strains that lack toxin production genes could be used to out compete bad strains and prevent recurrent CDI?

There is a new study just published in JAMA that evaluates the safety and efficacy of a nontoxigenic C. difficile strain M3 (VP20621; NTCD-M3) in preventing recurrent CDI in those patients initially treated with metronidazole and/or oral vancomycin. In the four-arms of the phase 2, double-blind placebo-controlled trial they compared patients given oral liquid formulation of NTCD-M3, 10^4 spores/day for 7 days (n = 43), 10^7 spores/day for 7 days (n = 44), or 10^7 spores/day for 14 days (n = 42), or placebo for 14 days (n = 44).

Recurrent CDI occurred in 13/43 (30%) of placebo patients and only 14/125 (11%) of patients treated with NTCD-M3 patients (odds ratio [OR], 0.28; 95% CI, 0.11-0.69; P = .006). Fecal colonization with the NTCD-M3 strain was reported in 69% of treated patients and was associated with lower recurrence: 2/86 (2%) recurrence if colonized vs. 12/39 (31%) recurrence in treated but uncolonized patients (OR, 0.01; 95% CI, 0.00-0.05). Side effects such as abdominal pain, diarrhea and serious side effects were actually higher in the placebo groups. If this smaller study's findings are confirmed in larger trials, we may just have a new treatment for the prevention of recurrent CDI. Very cool.

Check out the video interview with lead author Dr. Dale Gerding, another related video and the JAMA Associate Editor's podcast covering this article and other important studies.