ABSTRACT
ABSTRACT Within the last decade our understanding about the pathogenesis of bacterial respiratory tract infection has been substantially increased. Advances in molecular biology promoted the identification and functional analysis of microbial genes and their proteins involved in the development of pulmonary infection. Recent studies have elucidated several pathways of the host's innate immune system which is specialized in rapidly detecting foreign microorganisms, in phagocytosing and killing them, and in possibly evoking further adaptive mechanisms against them. Here, we will discuss the host response in bacterial pneumonia emphasizing pattern-recognition receptors, such as the Toll-like receptors, and downstream effects such as production of cytokines and antimicrobial peptides as well as apoptosis. We will also describe general bacterial virulence factors in pneumonia as well as species specific virulence factors of Streptococcus pneumoniae, the most common microorganism of community-acquired respiratory tract infection.
