“…The human body is colonized by a variety of microbes, including bacteria, fungi, virus, archaea, and protozoa (Grice and Segre, 2012, Sender et al, 2012, Debarbieux et al, 2017, Eckburg et al, 2003, most of which are found in the gastrointestinal tract (Shreiner et al, 2015). Healthy lungs were long considered to be sterile.…”