Two Coincidental Isolated Cases of Legionnaires' Disease Diagnosed by PCR and Cured by Combination Therapy with Clarithromycin and Rifampicin

We report 2 cases of Legionnaires' disease that occurred in the same town in Japan at the end of October, 1994. Patient 1 was a 66-year-old male with well-controlled diabetes mellitus, while patient 2 was a previously healthy 46-year-old male. Both patients developed fever and general fatigue on admission, accompanied by disturbances of consciousness in patient 2. The clinical course in both patients showed progressive hypoxemia, expansion of pulmonary infiltration on chest x-ray, severe inflammatory reactions including reduced peripheral lymphocytes, and elevation of transaminases, LDH, and CPK. Both patients recovered completely following the administration of clarithromycin and rifampicin. Although no organism of anyLegionella species was isolated from clinical specimens,Legionella rDNAs were detected by polymerase chain reaction amplification using LEG primers in bronchial secretions from patient 1 and a pleural effusion from patient 2, andLegionella pneumophila serogroup 1 antigen was detected in the urine and pleural effusion of patient 2. The microagglutination test for the detection of serum anti-Legionella antibodies confirmed that the causative organism in patient 1 wasL. pneumophila serogroup 4 orLegionella dumoffii, and in patient 2,L. pneumophila serogroup 1A, suggesting that the 2 cases did not represent an outbreak, but were isolated cases.