The most widely known model of the development of bronchiecta¬sis is Cole's ‘vicious cycle hypothesis’.15b According to this hypothesis an environmental insult, often against a background of genetic susceptibility, impairs mucociliary clearance, resulting in persistence of microorganisms in the bronchial tree and microbial colonization.The microbial infection causes chronic inflammation, resulting in tissue damage and impaired mucociliary motility. This then leads to more infection, with a cycle of progressive inflammation, causing lung damage.
Factors required for the development of this condition are persistent infection and a defect in host defences. The three most important mechanisms that contribute to the pathogenesis of bronchiectasis are infection, airway obstruction, and peribronchial fibrosis. In some cases, all three mechanisms are involved; in others, one is the …show more content…
In addition, some of the conditions associated with bronchiectasis, such as cystic fibrosis and dyskinetic cilia syndrome, are characterized by abnormal mucociliary clearance, and it is possible that this deficiency itself predisposes to local airway colonization. Pseudomonas aeruginosa is particularly important in this regard; as assessed by HRCT, its presence is associated with more extensive disease as well as thicker, more dilated airways.15kBranhamella catarrhalis has also been increasingly recognized as an important lower respiratory tract pathogen in bronchiectasis.15l Whatever the pathogenesis of the colonization, it is likely that the chronic inflammatory reaction to the organisms results in progressive bronchial wall damage and dilation; this can cause an even greater deficiency of mucociliary clearance,15mestablishing a vicious cycle and ever-increasing
Factors required for the development of this condition are persistent infection and a defect in host defences. The three most important mechanisms that contribute to the pathogenesis of bronchiectasis are infection, airway obstruction, and peribronchial fibrosis. In some cases, all three mechanisms are involved; in others, one is the …show more content…
In addition, some of the conditions associated with bronchiectasis, such as cystic fibrosis and dyskinetic cilia syndrome, are characterized by abnormal mucociliary clearance, and it is possible that this deficiency itself predisposes to local airway colonization. Pseudomonas aeruginosa is particularly important in this regard; as assessed by HRCT, its presence is associated with more extensive disease as well as thicker, more dilated airways.15kBranhamella catarrhalis has also been increasingly recognized as an important lower respiratory tract pathogen in bronchiectasis.15l Whatever the pathogenesis of the colonization, it is likely that the chronic inflammatory reaction to the organisms results in progressive bronchial wall damage and dilation; this can cause an even greater deficiency of mucociliary clearance,15mestablishing a vicious cycle and ever-increasing