ObjectiveTo investigate the etiologic feature and prognosis of adult patients with severe community-acquired pneumonia (SCAP). MethodsAccording to the guideline on the diagnosis and treatment of community-acquired pneumonia in 2006, 105 patients with SCAP were included in the study. The proportion of pathogens (including multiple resistant bacteria) and mortality rate were recorded. Appropriate statistical methods were selected and all data were analyzed by using SPSS Version 18.0 computerized program. ResultsThe predominant pathogen with SCAP was Pseudomonas aeruginosa, followed by Klebsiella pneumoniae, Staphylococcus aureus, and Legionella pneumophila. In death cases, Klebsiella pneumoniae was the most common pathogen, followed by Staphylococcus aureus. It was showed in the drug sensitivity test that most pathogens were drug-sensitive strains. The patients with tumor had higher risks to get infected with Gram-negative bacillus. ConclusionsThe etiology of patients with SCAP in our emergency department is given priority to Gram-negative bacillus and sensitive strains, of which Pseudomonas aeruginosa and Klebsiella pneumoniae are predominant. As for the Gram-positive cocci, Staphylococcus aureus is the most common pathogen. Legionella pneumophila is the most common pathogen in atypical pathogens, which only account for a small proportion of the aetiology of SCAP. Patients with Klebsiella pneumoniae and Staphylococcus aureus infections are associated with poor prognosis.