The enzyme immunoassay from Alere (Scarborough, Marine, USA),
which qualitatively detects the presence of L. pneumophila serogroup 1
antigen in urine, was performed according to the instruction of the
manufacturer. Briefly, urine samples were added together with anti-
Legionella HRP conjugate to themicrotitre wells, coated with polyclonal
antibodies raised against L. pneumophila serogroup 1 antigen. After 2 h
incubation, the plate was decanted and washed. A colour developer
was added. Following another incubation of 15 min the reaction was
stopped and the resultant absorbance read on a microplate reader at
450 nm