Comparison of diagnostic value of ELISA tests with Brucella serological tests in patients with brucellosis

Brucellosis is one of the most common infectious diseases transmitted from animal to human. Different methods of blood culture, serology, PCR and ELISA are used to diagnose brucellosis. The aim of this study was to compare the diagnostic value of ELISA tests with Brucella serological tests in patients with brucellosis.

In this cross-sectional descriptive study that was conducted from the beginning of April 2018 to the end of March 2019, 231 patients referred to the Infectious Diseases Clinic of Sina Hospital in Hamadan with clinical symptoms and possible diagnosis of brucellosis were included in the study. 5 cc of blood was taken from the patients to prepare serum, at the same time as Wright, Combs Wright and 2ME serology tests, IgG and IgM ELISA tests were also performed using the ELISA kit of Pishtaz Teb Company (Made in Iran), which is designed with the cut-off method. Then the test results were analyzed with SPSS software, version 16 (SPSS Inc., Chicago, IL, USA).

231 patients suspected of brucellosis including 147(63.64%) men and 84(36.36%) women with an average age of 44.60±16.16 years and a minimum of 10 years and a maximum of 80 years were examined. IgG and IgM results were positive with brucellosis in 80.1% and 30.30%, respectively. The results of IgG and IgM were positive in 1/80 and 30.30%, respectively, and they were diagnosed with brucellosis. In comparison with 2ME, Wright and Coombs-Wright serology tests, the sensitivity of IgG was between 83.80% and 94.28% and its specificity was between 20 and 33.34%, the sensitivity of IgM was also between 34.78 and 40.0% and its specificity was between 78.67% and 89.47% at different cut points.

Compared to diagnostic serological tests for brucellosis, IgG is more sensitive and IgM is more specific. If serological tests are not available, ELISA can be used to diagnose brucellosis. But because of their lower diagnostic value, they cannot be replaced.