A Case of Severe Legionella Pneumonia in Which Serial Testing by Ribotest ® Legionella was Useful for the Diagnosis.

A 79-year-old man presented with chest pain, and urinary antigen tests for Legionella pneumophila (ImmunoCatch Legionella and Ribotest Legionella) were negative on admission. The next day, rapid respiratory failure suggested Legionella pneumonia, and levofloxacin was added. Since a lung infiltration shadow appeared on the other side as well on day 4, non-infectious diseases were considered, and steroid therapy was started. Urinary antigen tests for Legionella pneumophila became positive on day 5. In the present case, retesting with Ribotest Legionella, which could be negative early after the disease onset, was useful for diagnosing Legionella pneumonia, which led to the discontinuation of unnecessary steroid treatment.