Figure 5

The potential spread of nontypeable strains of H . influenzae (NTHi) into the lung. A), Most healthy subjects have nasopharyngeal colonization with NTHi. A combination of bacterial pathogenic mechanisms and defects in host defense may allow NTHi to move down into the lower respiratory tract B). In the bronchi, NTHi may cause acute exacerbations of airway disease and/or chronic colonization. C), The bacterium may invade into bronchial cells such as macrophages or epithelial cells or D), may in more advanced lung disease invade into the parenchyma.