Diagnostic testing for community-acquired pneumonia

The clinical, radiographic, and routine laboratory features of community-acquired pneumonia can offer clues to the microbial cause of the infection, but a specific etiologic diagnosis requires the assistance of the microbiology laboratory. This article reviews the methods currently available for the microbiologic diagnosis of lower respiratory tract infection, including new methods for rapid diagnosis that are just entering the clinical laboratory. The role of invasive procedures in specimen procurement also is examined. Finally, the diagnostic challenges offered by specific common pathogens are considered in detail. By carefully evaluating the yields and limitations of the available tests, a reasonable approach to the diagnostic evaluation of the patient with community-acquired pneumonia can be formulated.