[Guideline 'Diagnosis and treatment of community-acquired pneumonia' from the Dutch Thoracic Society].

Community-acquired pneumonia (CAP) is associated with considerable morbidity and mortality. The incidence of CAP in the Netherlands is estimated to be 5-10 per 1000 per year. This guideline can be used for the scientifically-based diagnosis and antibiotic treatment of adults with CAP. Streptococcus pneumoniae is the most frequent causative agent In 30-50% of patients, the aetiological pathogen cannot be identified. In the Netherlands, the resistance of S. pneumoniae to penicillin is less than 1%. In addition to patient history and physical examination, chest radiography is indispensable to the diagnosis of CAP. Cultures of sputum, blood, and, if present, pleural effusion are needed to detect the causative agent. Bronchoscopy can be considered if the patient's condition deteriorates during antibiotic therapy. Urinary antigen detection is important if signs of legionellosis are present; only Legionella pneumophila serotype can be identified with this technique. The severity of CAP and the risk factors can be measured by the pneumonia severity index, which may be helpful in deciding whether to hospitalise a patient. The choice of antibiotic therapy is based on the intention of providing optimal therapy, the epidemiological features ofvarious microorganisms in the Netherlands, and an inference of the most likely pathogen, based on comorbidity. Empirical antibiotic therapy should target primarily S. pneumoniae because of its high incidence. In both seriously ill patients and those suspected of having legionellosis, antibiotic therapy should also target L. pneumophila. Antibiotic therapy should be adjusted if the pathogen is subsequently identified. Parapneumonic effusion frequently occurs in cases of CAP. Drainage is indicated if the pleural fluid contains bacteria or yields a pH < 7.0. Influenza vaccination is recommended in the elderly to prevent CAP.