Impaired Colonization Defence of the Oropharynx

Abstract

“Colonization” may be defined as the persistence of microorganisms at a particular site over time. To distinguish colonization from infection, the qualifiers “in the absence of tissue damage or a host response” are usually added. Colonization of certain sites in the human body is obviously normal, but colonization may be abnormal under a number of conditions. A body region may become colonized by organisms which are not normally found at that site. This is often, though not always, due to pre-existing tissue injury, as in the case of colonization of burned skin by Pseudomonas aeruginosa. Colonization of normally sterile sites is another form of abnormal colonization. Common sites for such colonization include the tracheobronchial tree, particularly in patients who have endotracheal tubes in place, and the urinary tracts of patients with indwelling catheters. It is often difficult to distinguish abnormal colonization from infection on the basis of a single observation, and it is probably true that abnormal colonization precedes infection in many clinical situations.