With the mapping of the human microbiome, a new understanding is emerging of the complex relationship between the microorganisms that live in the human gut, skin, and elsewhere on the body, and the role they play both in disease and in maintaining health. Along with growing concerns about drug resistant bacteria, this is giving rise to opportunities for narrow spectrum antibiotics. We spoke to David Martin, founder and CEO of AvidBiotics, about the problems of antibiotic resistance, the benefits narrow spectrum therapies offer, and how the sequencing of the microbiome is leading to new approaches to not only treat infectious diseases, but other diseases not traditional thought of as being driven by microorganisms.