The microagglutination test as a complement to ELISA examination in serological diagnosis of Legionella infections
Abstract number: 1135_157
Pancer K.W., Gut W., Stypulkowska-Misiurewicz H.
In Poland, laboratory diagnosis of Legionella infections generally is based on serological investigation. Bacteria L. pneumophila sg 1 are more frequent cause of severe pneumonia, less frequent are L. pneumophila other serogroups or other Legionella species. Examination of serum sample using ELISA IgA, IgM and IgG assays is the method of choice in our laboratory for detection L. pneumophila sg 1. For L. pneumophila non-1 or other Legionella species infection the microagglutination test has been used. In our study we determined the significant titre of serum antibody to some L. pneumophila non-1 serogroups and other Legionella species on the base of results of examinations of serum samples collected from blood donors. The titre of antibody was determined using 14 antigens prepared in-house from the reference strains L. pneumophila and others Legionella. Statistical analysis of obtained results allowed to determine cut-off titre for all used antigens. The value of cut-off was 64 for L. pneumophila sg 1, 2, 4, 5, L. longbachae, cut-off = 128 for L. pneumophila sg 3, 7, 8, L. micdadei, L. jordanis, and cut-off = 256 for L. pneumophila sg 6, 12, L. bozemanii, L. anisa. Using those cut-off points we are able to eliminate not significant titre due to some cross-reactivity of L. pneumophila serogroups. Determination of specific serum IgA, IgM and IgG antibody levels to L. pneumophila sg 1 by commercial ELISA is more sensitive, standarised, informative and faster than microagglutination test. However, from our point of view the microagglutination test should be used as complement test to ELISA, especially for diagnosis of infection due to L. pneumophila non-1 serogroups or other Legionella species. In 16% of all serum samples tested this year the significant titre of antibody specific to one of serogroup of L. pneumophila non-1 was found using MAT. In those sera increased but not significant level of IgM antibodies to L. pneumophila sg 1 (in range 0.320.75) or IgA antibodies (0.380.53) was determined by ELISA. It is probably connected with cross-reactivity of some antigenic structures of L. pneumophila strains. Moreover, two cases of legionellosis due to L. micdadei were diagnosed. In those cases the antibiotic had been changed and the patients recovered. Because of unspecific symptoms and rather high mortality rate in legionnaires disease the microbiological diagnosis of Legionella infection should be done using as many supplementary techniques as possible.
|Session name:||XXIst ISTH Congress|
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