Community-acquired pneumonia.

Community-acquired pneumonia (CAP) is one of the most common acute infections requiring admission to hospital. The main causative pathogens of CAP are Streptococcus pneumoniae, influenza A, Mycoplasma pneumoniae and Chlamydophila pneumoniae, and the dominant risk factors are age, smoking and comorbidities. The incidence of CAP and its common complications, such as the requirement for intensive care and complicated parapneumonic effusions, are increasing, making it essential for all physicians to have a good understanding of the management of CAP. Although the diagnosis and treatment of CAP is straightforward in most cases, it can be more complex, and recent data indicate that the mortality of CAP in the UK is surprisingly high. In the future, routine use of biomarkers to improve risk stratification and tailor management to individual patients could improve outcomes, and there is some evidence that modulation of CAP-associated inflammation could also be beneficial. Both research into host-microbial interactions in the lung and clinical trials of different management and preventative treatments are urgently needed to combat the increasing morbidity and mortality associated with CAP.