[Significance of Haemophilus influenzae and other microorganisms for the pathogenesis and therapy of chronic respiratory infection]

Abstract

The host's respiratory defence mechanisms are transformed to chronic inflammatory reactions by the persistence of microorganisms and hence inflict damage on the host's own tissues. This change primarily reduces the capability of the mucociliary defence mechanisms. Such impairment can result from modifications to the mucus's physical chemical properties after an infection, or from damage to the ciliary epithelium. Haemophilus influenzae, Pseudomonas aeruginosa and Streptococcus pneumoniae cause ciliary dyskinesia and eventually lead to the destruction of the ciliary epithelium. Encapsulated type b H. influenzae strains appear to slow down the cilia most markedly. There is a fundamental difference between acute and chronic infections. In the case of acute infections the patient's normal defence mechanisms are usually intact. In chronic infections the chronic inflammatory response to the microorganisms causes the disease to progress. In such cases treatment must be considerably more aggressive since the host's "cleansing" capability is diminished. Thus, antibiotics must be applied which can effectively penetrate the bronchial tree and which also remain stable and bioactive in the presence of beta-lactamase producing microorganisms such as H. influenzae. It is conceivable that, in the future, antibiotic therapy will have to be combined with antiphlogistic agents.