Emerging bacterial pathogens and changing concepts of bacterial pathogenesis in cystic fibrosis.

Chronic suppurative lower airway infection is a hallmark feature of cystic fibrosis (CF). Decades of experience in clinical microbiology have enabled the development of improved technologies and approaches for the cultivation and identification of microorganisms from sputum. It is increasingly apparent that the microbial constituents of the lower airways in CF exist in a dynamic state. Indeed, while changes in prevalence of various pathogens occur through ageing, differences exist in successive cohorts of patients and between clinics, regions and countries. Classical pathogens such as Pseudomonas aeruginosa, Burkholderia cepacia complex and Staphylococcus aureus are increasingly being supplemented with new and emerging organisms rarely observed in other areas of medicine. Moreover, it is now recognized that common oropharyngeal organisms, previously presumed to be benign colonizers may contribute to disease progression. As infection remains the leading cause of morbidity and mortality in CF, an understanding of the epidemiology, risk factors for acquisition and natural history of infection including interactions between colonizing bacteria is required. Unified approaches to the study and determination of pathogen status are similarly needed. Furthermore, experienced and evidence-based treatment data is necessary to optimize outcomes for individuals with CF.