Serum antibodies to Legionella pneumophila by indirect immunofluorescent antibody test in 269 hemodialysis patients and 353 healthy subjects

Serum antibodies to Legionella pneumophila serogroup I-VI were determined by indirect immunofluorescent antibody test in 269 hemodialysis patients and compared to 353 so called healthy subjects. Antigen suspension was prepared by incubation on B-CYE agar and adding formalin solution, then fixed on a micro slide glass, and reacted with serial serum dilutions. FITC-labeled goat antihuman immunoglobulin was added as a second antibody. 273 (77.3%) cases of control group had a titer of less than 1:4, 6 (1.7%) cases had a titer of 1: 32, and none had a titer of greater than or equal to 1: 64. There was no significant difference in sex and age. 173 (64.3%) hemodialysis patients had a titer of less than 1: 4, 13 (4.9%) cases had a titer of greater than or equal to 1: 64, and 5 (1.9%) cases had a titer of 1: 128, 42 (43.8%) of 96 cases who showed a titer of greater than or equal to 1: 4 had antibodies to Legionella pneumophila serogroup I. The titer in hemodialysis patients were higher than control group (p less than 0.005). The results of this study suspected that acute feverish disease and pneumonia of compromised host such as hemodialysis patients should be always thought of Legionnaires' infection.