Pharmabiotic Manipulation of the Microbiota in Gastrointestinal Disorders: A Clinical Perspective

The advent and widespread availability of high-throughput technology has revolutionized the assessment of the communities of microorganisms that inhabit the gastrointestinal tract--the gut microbiota. As our understanding of the role of the microbiota in health and human disease increases, so also do efforts to prevent and treat disease through the modulation of the microbiota. Several strategies are available to us and range from time honored approaches, such as antibiotics and probiotics, to changes in diet, the administration of prebiotics as food supplements, and fecal microbiota transplantation. Of these, diet is perhaps the most pervasive but often ignored modulator of the microbiota, and a failure to recognize its impact complicates the interpretation of many microbiota studies. The impacts of antibiotics on the microbiota are more complex than originally thought and, though antibiotics can be life-saving, their effects on commensal bacterial populations can be clinically significant. Though there have been many studies of, and even more claims made for, probiotics, the majority of available studies suffer from significant deficits in study design and execution and many claims remain to be substantiated. Though holding much promise, the study of prebiotics in human disease is still in its infancy. Possibilities other than the administration of live organisms have been identified through efforts to mine the microbiota for novel therapeutics and include: dead organisms, bacterial components, small molecules elaborated by bacteria, and even bacterial DNA. Accordingly, the term pharmabiotic has been introduced to encompass the full range of therapeutic possibilities that the microbiota offers.