Serological tests for Legionella pneumophila serogroup 1 infections.

The indirect fluorescent antibody test (IFAT) using a formolised yolk sac antigen (FYSA) has been shown to be a sensitive, specific test for legionellosis and results obtained on the same serum specimens in different laboratories agree closely. The rapid micro-agglutination test (RMAT) has the advantage of being semi-automatable and also sensitive and specific. Both tests gave negative results with sera from patients with infections due to Mycoplasma pneumoniae, Chlamydia psittaci, Coxiella burnetti and other agents.