A Case of Legionella Pneumonia in Which Legionella Antigen Was Detected in BALF Using a Legionella Urinary Antigen Test Kit

• Published in: The Journal of the Japan Society for Respiratory Endoscopy Vol. 43; no. 2; pp. 150 - 155
• Main Authors: Masuno, Tomoaki, Shigenaga, Takehiko, Nishiyama, Yoshiki, Tanaka, Ai, Fujishima, Nobuhiro, Miyazaki, Shuya, Itai, Mariko, Hata, Masahiro, Kadota, Junichi
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society for Respiratory Endoscopy 25.03.2021
• Subjects: Bronchoalveolar lavage fluid; Legionella pneumonia; Urinary antigen test
• ISSN: 0287-2137; 2186-0149
• DOI: 10.18907/jjsre.43.2_150

Background. Legionella pneumonia-when not properly treated-is associated with a high rate of mortality; thus, an early diagnosis and treatment are critical. In some cases, however, an early diagnosis may be difficult to make. Case. A 53-year-old Japanese man who visited a local hospital with a chief complaint of fever, was diagnosed with bacterial pneumonia and was given ceftriaxone; however, his condition did not improve. He was therefore transferred to our hospital for treatment. The initial antibiotic treatment failure and chest CT imaging suggested organizing pneumonia as a probable diagnosis. In order to distinguish between bacterial infection and organizing pneumonia, we performed bronchoalveolar lavage (BAL) soon after his arrival at our hospital. We could not perform a Legionella urinary antigen test because we could not obtain a urine sample. Thus, we performed the Legionella antigen test using bronchoalveolar lavage fluid (BALF) as a substitute for urine on a trial basis. Based on the positive test result, we suspected legionella pneumonia. The diagnosis of legionella pneumonia was subsequently confirmed by the analysis of a urine sample using a Legionella urinary antigen test. We immediately started treatment with levofloxacin and azithromycin. He made a good recovery and was discharged on the ninth hospital day. Conclusion. When a urine sample cannot be obtained in a case of suspected legionella pneumonia, BALF can be substituted for urine for the Legionella urinary antigen test.