Legionella and community-acquired pneumonia: A review of current diagnostic tests from a clinician's viewpoint

Many physicians are unaware of the limitations of the available tests for d iagnosing infections with Legionella organisms. Geographic differences in t he importance of nonpneumophila Legionella species as pathogens are underre cognized, in part because available diagnostic tests are biased toward the detection of pneumophila serogroup 1. Routine laboratory practices reduce t he likelihood of culturing Legionella species from clinical isolates. Failu re of seroconversion is common, particularly with nonpneumophila species; e ven when seroconversion occurs, it may take much longer than 4 weeks. Urina ry antigen testing has insufficient sensitivity to affect clinical manageme nt in most regions of the United States, as it can reliably detect only L. pneumophila serogroup 1 infections. Polymerase chain reaction-based techniq ues offer hope of providing highly sensitive, rapid diagnostic tests for al l Legionella species, but limitations in the current tests will make valida ting them difficult. (C) 2001 by Excerpta Medica, Inc.