A spin-off approach is passive immunotherapy using just antibodies to C. difficile toxins. Studies have shown that humans produce large quantities of antitoxin IgG after immunization. Researchers at Acambis are currently investigating a vaccine with antitoxin A and antitoxin B IgG.
Researchers are also investigating animal-derived hyperimmune antitoxin products, such as a whey protein concentrate made from the milk of cows vaccinated with C. difficile toxoids. The product appears to help prevent CDAD relapse, based on data from a pilot study (J. Med. Microbiol. 2005;54:197–205).
▸ Fecal flora restoration. Fecal restoration is also being investigated as an effective—albeit unpleasant—therapy for CDAD. The idea is to use enemas of normal stool to restore normal fecal flora. Anecdotal and small series reports show a good response in patients with recurrent CDAD. One study also showed that it is possible to give donor stool via a nasogastric tube.
Dr. Miller disclosed that he is a consultant for and/or holds research grants from ActivBiotics Inc., Advanced Biologics, Bayer, BD's GeneOhm, Conagra Foods Inc., Genzyme Corporation, GlaxoSmithKline, Janssen-Ortho Inc., LDI