Evaluation of a solid-phase immunofluorescence assay for detection of antibodies to Legionella pneumophila

A semiautomated solid-phase immunofluorescence technique (FIAX) was compared with the standard indirect immunofluorescence assay (IFA) for the determination of antibody levels to Legionella pneumophila serogroup 1 in paired human serum samples. The FIAX method was in agreement with the IFA test for 91.8% of the serum pairs but gave evidence of a recent Legionella infection significantly fewer times than did the IFA. These results suggest that the FIAX technique may eventually be a useful alternative test for measuring Legionella antibodies. However, further study will be required to determine its efficacy in providing a serodiagnosis of legionellosis.