[Harnessing nature for treating infectious and autoimmune diseases: good and bad bacteria]

Clostridium difficile is the etiologic agent of nosocomial and community-acquired diarrhea associated with exposure to antibiotics that disrupt the normal colonic flora. As antibacterials currently used for primary C. difficile infections favor recurrences, new methods able to neutralize the bacterium without affecting the gut microbiota are badly needed. Complementary treatment with probiotic agents to reconstitute the physiologicaL intestinal flora does not yield any consistent benefit. In recent years, fecal transplantation has been used in the English-speaking countries with cure rates of about 87%. Fecal microbiota transplantation (FMT) holds considerable promise as a therapy for recurrent Clostridium difficile infection, but well-designed, randomized-controlled trials and Long-term follow-up registries are stilt required. These are needed to identify the right patient, efficacy and safety profile of FMT before this approach can be widely advocated. Another aspect of bad/good parasites are the use of helminth or helminth ova for treating autoimmune diseases, especially those affecting the gut.