Community-acquired pneumonia: the future of the microbiology laboratory: focused diagnosis or syndromic management?

The traditional classification of community-acquired pneumonia into typical and atypical pneumonia to facilitate successful empirical treatment is no longer optimal. An accurate prediction of cause and adequate empirical therapy cannot be provided with this approach in severely ill patients. There is an increasing spectrum of recognized treatable pathogens presenting as community-acquired pneumonia including Legionella species, Chlamydia pneumoniae, and Pneumocystis carinii in addition to the traditional community pathogens. The variability of presentation in severely ill or compromised hosts makes clinical prediction of cause inadequate. A more rational approach may involve the classification of patients by the severity of illness and underlying disease with little or no microbiological workup in mild illness unless the results will contribute to the epidemiological surveillance of resistance because these investigations have not been shown to affect outcome in this setting. Etiologic diagnosis should be more aggressively sought and the microbiology laboratory can be best used by providing the efficient and rapid diagnosis of this expanded range of pathogens in more severely ill patients. The mounting antimicrobial resistance of common pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus will require not only a critical review of empirical therapy, but an increased emphasis on epidemiological monitoring of resistance by laboratories and effective communication with clinicians.