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Laboratory Diagnosis of Legionnaires' Disease
in Patients with Community Acquired Pneumonia (CAP)
S. Kanavaki, S. Karabela, M. Makarona, S. Triantafillou,
E. Efstathiadou, P. Koumantakis, M. Panagi, E. Anastasakou
Microbiology Department, "Sotiria" Hospital
SUMMARY: The outcome of legionnaires' disease depends largely on the
timely laboratory diagnosis for the early initiation of appropriate management.
We performed and evaluated the currently available tests for the diagnosis of
Legionella infection in 88 patients suffering from severe community-acquired
pneumonia and hospitalized in "Sotiria" Athens Hospital. In particular,
we evaluated the methods of Legionella antigen detection in sputum by
DFA staining, serological testing by ELISA, and IFA assay for soluble Legionella
urinary antigen using either ELISA (Biotest EIA) or the new rapid immunochromatographic
assay (ICT-Binax NOW). Detection of Legionella antigen by DFA staining
gave the poorest positive result rate (4.3%), while both serology testing and
detection of urinary antigen were positive in six patients (6.8%). The main
difference lied in the time in which results were obtained, with urinary antigen
detection being significantly more rapid, regardless of the methodology used.
It is therefore concluded that urinary antigen detection is an important tool
for the diagnosis of legionnaires' disease and should never be neglected. Interestingly,
the ICT-Binax NOW assay seems to be more practical, since results are obtained
in much shorter time and it is easier to perform, whereas no special equipment
or technical expertise is required and its sensitivity compares well to that
of Biotest EIA. Pneumon 2003, 16(2):181-188.
Key words: Legionella pneumonia, urinary Legionella antigen,
rapid immunochromatographic assay, microbiological diagnosis of Legionella
infection.
Correspondence: Sophia Kanavaki, Assistant Director, Microbiology Department,
"Sotiria" Hospital, 152 Messogion Ave., GR-11527 Athens, Greece.
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