Comparison of standard agglutination tests, enzyme immunoassay, and Coombs gel test used in laboratory diagnosis of human brucellosis

Abstract

Background/aim: It was aimed to evaluate the results of Rose Bengal (RB), ELISA total tests (IgM and IgG), and the Brucella Coombs gel test (BCGT), which are used as screening tests, with the combined results of a tube agglutination test (standard Wright test: SWT) and a tube agglutination test with antihuman globulin (AHG TAT). Materials and methods:Samples from 97 patients prediagnosed with brucellosis (age ≥18 years) were screened with RB, ELISA, and BCGT. SWT < 160 samples and RB-negative but ELISA-or BCGT-positive samples were tested by AHG TAT. SWT ≥ 160 or AHG TAT ≥ 160 was taken as reference.Results: Thirty-two of 56 RB-positive samples and one RB-negative but ELISA-and BCGT-positive sample were found to be ≥160 with SWT or AHG TAT. Sensitivity, specificity, accuracy, and agreement (kappa) values according to SWT ≥ 160 or AHG TAT ≥ 160 positivity were as follows, respectively:

A comparison of a new diagnostic test of the human Brucellosis, the Brucella Coombs Gel Test, with other methods

“…A study performed in 2015 [24] reported that BCGT was in excellent agreement with the Brucella immuncapture test (K=0.979). Another study [5] stated similar findings as with others, that BCGT was in almost perfect agreement with classic coombs test (K=0.846), though Koçman et al [16] detected that the BCGT (above 1/160) was in good agreement with Brucella immuncapture test (K=0.724). In our study, we detected that there was an excellent agreement between the BCGT and BCAP tests with the following Kappa test findings: K=0.824.…”

“…The results were closely similar; however, only a study reported [16] that the sensitivity of BCGT was 78.8%, if the titer was above 1/160, and the accuracy of this test was 88.7%. In our study, we compared the positivity results of BCGT to BCAP.…”

“…Another study reported that the sensitivity, specificity, positive and negative predictive values of the Coombs gel test were 100%, 82.2%, 84.3%, and 86%, respectively [23]. The results were closely similar; however, only a study reported [16] that the sensitivity of BCGT was 78.8%, if the titer was above 1/160, and the accuracy of this test was 88.7%. In our study, we compared the positivity results of BCGT to BCAP.…”

“…The diagnosis of brucellosis in clinic is quite difficult especially in the absence of specific clinical features. At that point, specific microbiological tests should be used to diagnose the probable brucellosis in order to prevent the problems associated with the treatment processes and responses [15][16][17]. These diagnostic tests are the Rose Bengal test [18], the standard tube agglutination test [10], the immuncapture test [19] and the ELISA test [20].…”

Brucellosis Testicular Abscess: Case Report

“…In addition to the patient's history and physical examination findings, some tests, such as the Rose Bengal test, Brucella tube agglutination test, Coombs test, and blood culturing, are required for the diagnosis of brucellosis (9). Blood culturing is the gold standard for the diagnosis of brucellosis; however, it is difficult to cultivate the bacteria owing to the long incubation period, them being biosafety level 3 organisms, antibiotic susceptibility, the culture medium, and the need for specialized and experienced personnel (10,11). In chronic cases, the culturing often fails or takes a long time.…”