Which areas likely do NOT contain resident microorganisms?
The urogenital, biliary, pancreatic ductal, and distal respiratory tracts do not possess resident microflora in healthy individuals, although microbes may be present if these barriers are affected by disease ( eg, malignancy, inflammation, calculi, or foreign body), or if microorganisms are introduced from an external source ( eg, urinary catheter or pulmonary aspiration). In contrast, significant numbers of microbes are encountered in many portions of the gastrointestinal tract, with vast numbers being found within the oropharynx and distal colorectum, although the specific organisms differ.