Infective pathogenesis and outcomes in chronic bronchitis.

Bacterial infection is an important cause of exacerbations of chronic bronchitis, which can precipitate both direct toxic and host-mediated inflammatory bronchial epithelial damage. Repeated episodes, especially when caused by Haemophilus influenzae (the major pathogen) may be associated with more rapid deterioration in respiratory function. Criteria to identify patients with more severe disease and those who require either hospitalization or intensive care have been developed and can improve mortality. Antibiotic therapy has an accepted place in management, and predictors of the outcome of exacerbations have now been developed that allow severity staging of individual episodes. Nevertheless, despite the recognition of excessive failure rates due to increasing bacterial resistance and poor respiratory kinetics, many patients continue to receive empiric therapy with amoxicillin and other oral beta-lactams. Less empiric management guidelines, produced in Europe and North America and based on such criteria, now provide a framework for rational prescribing. Perhaps more importantly, it is now possible to design and perform placebo- and comparator-controlled studies of new antibacterials, such as the fluoroquinolones and azalides, with improved potency and kinetic properties. This will enable both an assessment of their place in the management of exacerbations in at-risk patients with severe disease and an evaluation of their longer-term role in the prevention of a decline in respiratory function consequent upon repeated and ineffectively treated exacerbations.