[A Case of Severe Legionella longbeachae Pneumonia and Usefulness of LAMP Assay].

Urinary antigen test is frequently used as a routine laboratory test for early diagnosis of Legionella infection , which is especially suitable for ordinary Legionella pneumophila serogroup 1, but not for other types of Legionella . We report a case of severe pneumonia caused by Legionella longbeachae , where a method of loop-mediated isothermal amplification (LAMP) assay contributed an important role for the early detection. This case involved an 83-year-old man who developed fever, dyspnea, and productive cough. Since the medication of prescribed ceftriaxone had not been effective, he visited the emergency room of our hospital, where an X-ray revealed a severe pneumonia harboring a consolidation with air bronchogram in his right lower lung. His sputum and urine were subjected to the routine bacterial culture or the urinary antigen test for Legionella , which initially brought negative results. However, a positive result of LAMP assay enabled early diagnosis of Legionella pneumonia . Later, the bacterial cultures of sputum made some progress and 16S rRNA sequencing provided a proof of L. longbeachae . This LAMP assay may bring a benefit for the patients with Legionella pneumonia by enabling early detection of not only specific L. pneumophila serogroup 1, but also of the other Legionella species.