Chapter 6 Microbiology of non - CF bronchiectasis

Non-cystic fibrosis (CF) bronchiectasis is a complex disorder characterised by recurrent chest infections and poorly regulated respiratory innate and adaptive immunity. These lead to a ‘‘vicious cycle’’ of impaired mucociliary clearance, chronic infection, bronchial inflammation and progressive lung injury. The most prevalent pathogenic bacteria are Haemophilus influenzae, Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus and Moraxella catarrhalis although variations in sampling techniques and detection methods have influenced their isolation rates. These organisms can inhibit mucociliary clearance, destroy respiratory epithelium and produce biofilms that promote persistent infection by blocking innate immune defences and increasing antibiotic resistance. While numerous studies have examined the role of different bacteria in CF and chronic obstructive pulmonary disease, little is known about how they contribute to the pathogenesis of nonCF bronchiectasis. There is also a paucity of data regarding the role of respiratory viruses in this condition. This chapter describes the microbiology of non-CF bronchiectasis, defines the bacterial mechanisms that may contribute to persistent infection and airway damage and discusses the potential role for respiratory viruses in this condition. Understanding the pathogenic properties of these microorganisms may allow the development of novel therapies for the management of respiratory exacerbations.