A case of severe pneumonia caused by Legionella longbeachaewith positive results by a Legionellaurinary antigen detection kit

Legionella longbeachaeis a Legionellabacteria often detected in soil, and is known as a rare cause of Legionellainfections in Japan. In addition, detection of this Legionellaspecies is often overlooked due to negative results from Legionellaurinary antigen tests, which could lead to errors in the therapeutic approach. An 80-year-old woman was admitted to our hospital because of fever and dyspnea. Her blood tests showed elevated white blood cells, increased C-reactive protein and transaminases, and hyponatremia. Chest computed tomography showed dense consolidation in the right lung. We diagnosed Legionellapneumonia because the Legionellaurinary antigen test was positive on the day after her admission. The patient was intubated and mechanically ventilated on the third day of hospitalization, because of respiratory failure. However, her condition did not improve and she died on the 10th day after admission. After her death, L. longbeachaewas detected from sputum culture from her tracheal tube, and was diagnosed as the causative organism of her pneumonia. L. longbeachaeinfection reportedly rarely produces positive urinary antigen test results. Our experience suggests that the urinary antigen test using Ribotest Legionella might be able to detect Legionellaspp. other than L. pneumophila.