A bacterial infectious disease that results in infection by bacteria which are part of the normal human flora when one or more of the defense mechanisms designed to restrict them from the usually sterile internal tissues are breached by accident, by intent (surgery), or by an underlying metabolic or an infectious disorder. [ DOID:0050339 http://books.google.com/books?id=mgmataMQjMwC&pg=PA388&lpg#v=onepage&q&f=false ]