A nonaggressive strain of clostridium difficile reduces the risk of recurrence of C. difficile infection, according to a JAMA study released May 5. CDI is responsible for 29,000 U.S. deaths each year. It is one of the most common and deadly healthcare-related infections, and clinical CDI has a recurrence rate of 25% to 30% among affected patients, the study stated.
From June 2011 to June 2013, researchers randomly assigned 173 adult patients ages 18 or older diagnosed as having CDI to receive one of four treatments: oral liquid formulation of nontoxigenic C. difficile strain in three varied doses and durations, or placebo. Prior to enrollment, the patients had successfully completed treatment with metronidazole, oral vancomycin or both at 44 study centers in the U.S., Canada and Europe.
Humans and hamsters
Researchers stated that gastrointestinal colonization by nontoxigenic C. difficile strains in both humans and hamsters had promising results, in previous studies, as a potential way to prevent CDI.
Patients received either oral liquid formulation of nontoxigenic C. difficile strain M3 (VP20621; NTCD-M3), 10,000 spores a day for 7 days, 10,000,000 power spores a day for 7 days, 10,000,000 spores a day for 14 days, or placebo for 14 days.
CDI recurrence was 30% among patients receiving placebo compared with 11% among patients receiving NTCD-M3. The lowest recurrence was in 5% of patients receiving 10,000,000 spores a day for 7 days.
Fecal colonization with NTCD-M3 occurred in 69% of NTCD-M3 patients; 71% with 10,000,000 power spores a day and 63% with 10,000 spores a day.
Adverse side effects were reported in 78% of NTCD-M3 patients and 86% of placebo patients. Diarrhea and abdominal pain were reported in 46% and 17% of patients receiving NTCD-M3 and 60% and 33% of placebo patients, respectively.
Seven of the placebo patients and three of the NTCD-M3 patients had serious treatment-emergent adverse events. Headache also was reported in a small percentage of each patient population.
Researchers are not certain how prevention occurs, but believe there may be an association with the presence of NTCD in the stool (colonization) with reduced infection from toxigenic C. difficile and in animal models with prevention of CDI when challenged with toxigenic strains.
“The most likely hypothesized mechanism of action of NTCD-M3 is that it occupies the same metabolic or adherence niche in the gastrointestinal tract as does toxigenic C. difficile and, once established, is able to outcompete resident or newly ingested toxigenic strains,” researchers stated in the study.
Authors concluded treatment appeared to be well tolerated and safe, but noted their study was conducted on a small sample size. Findings should be confirmed by larger studies.
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