Sero diagnosis of Legionella infection in community acquired pneumonia.
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Date
2010-01
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Abstract
Background & objectives: Legionella pneumophila has been increasingly recognized as an emerging
pathogen responsible for community acquired pneumonia (CAP) worldwide. In India, the actual burden
is not known. The present study was thus undertaken to see the presence of Legionella infection in
patients with community acquired pneumonia admitted in a tertiary care centre in north India.
Methods: Both children and adults (n=113) with symptoms of pneumonia were included in the study.
Clinical samples (blood, urine, nasopharyngeal aspirates, bronchoalveolar lavage, sputum, etc.) were
collected and subjected to culture and other tests. Enzyme linked immunosorbent assay (ELISA) was
done by commercial kits for all the three classes of immunoglobulins (IgG, IgM & IgA). Urinary antigen
was also detected using commercial kits. Culture was performed on 51 respiratory tract fluid samples.
Serum samples of 44 healthy controls were also screened for the presence of anti-legionella antibodies
(IgG, IgM & IgA).
Results: Thirty one of the 113 cases (27.43%) were serologically positive. Anti-legionella IgG, IgM and IgA
antibodies were positive in 7.96, 15.92 and 11.50 per cent patients respectively. In controls, seropositivity
was 9.09 (4/44). IgA was positive in 3 and IgM, IgG combined in one. Antigenuria detection by Microwell
ELISA kit showed 17.69 per cent positivity. Four antigenuria positive patients were also serologically
positive; of these two patients were positive for IgM, hence considered as confirmed cases of Legionella
infection. None of the sample was culture positive.
Interpretation & conclusions: Combination of serology and antigenuria detection may be a valuable tool for
the diagnosis of Legionella infection in absence of culture positivity. In order to evaluate the actual burden
of Legionella in community acquired pneumonia, further studies with larger samples need to be done.
Description
Keywords
Antigenuria, community acquired pneumonia, ELISA, immunoglobulins, Legionella pneumophila
Citation
Javed Sabah, Chaudhry Rama, Passi Kapil, Sharma Sutikshan, Padmaja K, Dhawan Benu, Dey A B. Sero diagnosis of Legionella infection in community acquired pneumonia. Indian Journal of Medical Research. 2010 Jan; 131(1): 92-96.