ABSTRACT
This chapter describes the anatomy and physiology of the respiratory system, the respiratory tract as a microbial habitat and the nature of the microbial communities inhabiting different regions of the respiratory tract. It explores what microbes get up to in the respiratory tract, the role of the respiratory microbiota in human health, diseases caused by the respiratory microbiota and dysbiosis of respiratory communities. All ten Toll-like receptors are expressed by airway epithelial cells and these are thought to play an important role in regulating the composition of the indigenous microbiota although the means by which they do so remains largely unresolved. The administration of antibiotics to children can have a profound effect on the respiratory microbiota but this depends very much on the antimicrobial spectrum of the particular antibiotic. The effects of antibiotic administration on the respiratory microbiota of adults have been investigated in a very limited number of studies.
