COPD is the third leading cause of death worldwide and a major cause of morbidity. Infection complicates
COPD, both when patients are stable and during exacerbations. Exacerbations drive disease progression, lung function
decline and premature death, therefore understanding and targeting airway infection are considered crucial. The
interactions of bacteria, viruses and airway inflammation have all been shown to be a factor in stable COPD and in
exacerbations. New molecular microbiology techniques are changing our view of COPD, identifying new bacterial
species and a diverse microbiome which can be disturbed in chronic lung disease.
Bronchiectasis is increasingly recognized in COPD, and may be a distinct sub-type or “phenotype” of disease associated
with greater bacterial colonization and inflammation. Increasingly, severe infections, and particularly pneumonia are
recognized as common in COPD, and the role of inhaled corticosteroids in provoking bacterial colonization and
development of pneumonia requires careful consideration. Long term antibiotic therapies are being explored as a means to
prevent exacerbations and disease progression in COPD. This paper brings together the current knowledge related to the
role of infection in COPD.