Diagnostic tests for CAP: current approaches and future perspectives

Diagnostic testing in community-acquired pneumonia (CAP) serves three functions: firstly, to confirm the presence of CAP; secondly, to assess severity; and thirdly, to identify the causative pathogen. Available techniques are satisfactory to fulfill the first two roles but are seriously inadequate as regards the third. Accordingly, antibiotic therapy for CAP must be empirical, at least initially. This article reviews current diagnostic methods and provides suggestions for appropriate use of diagnostic tests in CAP. The shortcomings of the available methods for microbiologic diagnosis are discussed. The potential for PCR to become the much sought after 'ideal' test for microbiologic diagnosis in CAP is explored.