Microbiota transplantations

The extreme importance of human bacterial ecosystems is increasingly recognized. Our various microbiota - the immense bacterial populations with which we live in constant symbiosis and which play a major role in our physiological equilibrium - have been attracting particular attention since 2005, particularly well beyond the classic infectious diseases which until now have viewed bacteria with a very negative a priori. This is all the more true as techniques for studying human microbiota are becoming ever more effective. Metagenomics (a molecular method) has enabled considerable progress, and now advances in microbial culture mean that many more fastidious bacteria can be isolated. At the same time, numerous studies have highlighted the occurrence of profound imbalances in our mucosal and skin bacterial ecosystems in a number of pathologies: Clostridium difficile colonization after antibiotic therapy, diabetes, obesity, neurodegenerative diseases, colorectal cancer for the intestinal bacterial ecosystem; vaginosis (vaginal dysbiosis), in which the imbalance of the microbiota is both qualitative and quantitative, with a decrease, or even disappearance, of a healthy, predominantly lactobacillary microflora replaced by an anaerobic polymicrobial flora with Gardnerella vaginalis, Prevotella bivia and Atopobium vaginae in particular; or finally for the skin flora associated with psoriasis and atopic dermatitis. So when a pathology dependent on a profound imbalance in an ecosystem is demonstrated, it becomes a therapeutic target, and a transplant of the microbiota of a "healthy" individual can then be envisaged.