[The value of the immunoglobulin G avidity test for the serologic diagnosis of brucellosis].

Abstract

In order to investigate the value of immunoglobulin G (IgG) avidity test for the serological diagnosis of Brucella infections, a total of 118 patients (74 male, 44 female; mean age: 43 +/- 18.7 years) were included into the present study. The patients have been diagnosed with the characteristic clinical findings, > or = 1/160 antibody titers in standard tube agglutination (STA) test and/or blood culture positivities. Brucella spp. have been grown in blood cultures of 78 patients, and STA test results were found positive (> or = 1/160 titers) in 117 patients. The diagnosis of a patient with 1/80 STA titer was based on the blood culture positivity. By enzyme immunoassay (ELISA), 3 patients (2.5%) were found positive for IgM, 14 (11.9%) were positive for IgG, and 101 (85.6%) were positive for both IgM and IgG. The patients who were found IgG positive have been grouped according to their duration of complaints. Group 1 included 99 patients with the history of brucellosis < or = 6 months, and group 2 included 16 patients with the history of brucellosis > 6 months. IgG avidity test was performed by ELISA in 115 IgG positive serum samples, with the denaturation substance (8 M urea). The cut-off value for IgG avidity index (AI) was accepted as 40%, and the avidity maturation period was defined as 6 months. As a result, the rates of patients who had low IgG AI in group 1 and 2 were found as 91.9% and 43.7%, respectively, while these rates were 8.1% and 56.3% for the presence of high IgG AI, respectively. The rate of low AI in group 1 was an expected result, while the rate was more than expected in group 2, indicating that Brucella antibodies with low avidity indices would not be helpful for the diagnosis of a recent infection, while Brucella antibodies with high avidity indices would be useful for the elimination of a recent infection.

• Authors: Selda Sayin Kutlu, Aysel Celikbaş, Onder Ergönül, Murat Kutlu, Sebahat Aksaray, Engin Güvener, Başak Dokuzoğuz
• Journal: Mikrobiyoloji bulteni (Mikrobiyol Bul) Vol. 37 Issue 4 Pg. 261-7 (Oct 2003) ISSN: 0374-9096 [Print] Turkey
• Vernacular Title: Brusellozisin serolojik tanisinda immünoglobulin G avidite testinin değeri.
• PMID: 14748263 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Antibodies, Bacterial
• Immunoglobulin G
• Immunoglobulin M

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Agglutination Tests
• Antibodies, Bacterial (blood)
• Antibody Affinity
• Bacteremia (microbiology)
• Brucella (immunology, isolation & purification)
• Brucellosis (blood, diagnosis, immunology)
• Enzyme-Linked Immunosorbent Assay
• Female
• Humans
• Immunoglobulin G (blood, immunology)
• Immunoglobulin M (blood)
• Male
• Middle Aged
• Time Factors