Clinical and Laboratory Diagnosis of Legionella Pneumonia

Abstract

Legionella pneumonia is a relatively rare but extremely progressive pulmonary infection with high mortality. Traditional cultural isolation remains the gold standard for the diagnosis of Legionella pneumonia. However, its harsh culture conditions, long turnaround time, and suboptimal sensitivity do not meet the clinical need for rapid and accurate diagnosis, especially for critically ill patients. So far, pathogenic detection techniques including serological assays, urinary antigen tests, and mass spectrometry, as well as nucleic acid amplification technique, have been developed, and each has its own advantages and limitations. This review summarizes the clinical characteristics and imaging findings of Legionella pneumonia, then discusses the advances, advantages, and limitations of the various pathogenetic detection techniques used for Legionella pneumonia diagnosis. The aim is to provide rapid and accurate guiding options for early identification and diagnosis of Legionella pneumonia in clinical practice, further easing healthcare burden.

Keywords: Legionella pneumonia; clinical characteristics; imaging findings; pathogenetic diagnosis.

Figure 1

The epidemiological characteristics and risk factors (left) and the various pathogenetic detection methods available for Legionella pneumonia (right). The epidemiological characteristics mainly refer to contaminated water sources (e.g., rain, pipes, air-conditioning systems), summer, warm and humid soil, and water births. The risk factors include age, gender, smoking, alcoholism, immunosuppression, and comorbid chronic cardiopulmonary disease. PCR, polymerase chain reaction. LAMP, loop-mediated isothermal amplification. mNGS, metagenomics next-generation sequencing. DFA, direct fluorescent. IFA, indirect immunofluorescence assay. EIA, enzyme immunoassay. ELISA, enzyme linked immunosorbent assay.