The microbiome consists of microbes that are both helpful and potentially harmful. Most are symbiotic (where both the human body and microbiota benefit), and some, in smaller numbers, are pathogenic (promoting disease). In a healthy body, pathogenic and symbiotic microbiota coexist without problems. But dysbiosis stops these normal interactions if there is a disturbance in that balance -- brought on by infectious illnesses, certain diets, or the...