Evaluation of an Immunocapture-Agglutination Test (Brucellacapt) for Serodiagnosis of Human Brucellosis

Abstract

We evaluated the validity and the usefulness of a new test for the diagnosis of human brucellosis based on an immunocapture-agglutination technique. A total of 315 sera from 82 patients with a diagnosis of brucellosis, 157 sera from patients in whom brucellosis was suspected but not confirmed, and 412 sera from people living in rural areas with endemic brucellosis were studied. The seroagglutination test (SAT), Coombs anti-Brucella test, and Brucellacapt test were evaluated. All the initial sera from the 82 patients proved to be positive in Brucellacapt and Coombs tests, while only 75 (91.4%) were positive in the SAT. If a ≥1/160 diagnostic threshold titer was defined for the Brucellacapt test, Coombs test, and SAT, the sensitivities were 95.1, 91.5, and 65.8%, respectively. Taking the same diagnostic threshold titer for the 157 sera from the unconfirmed but suspected patients, the specificities of the Brucellacapt, Coombs, and SAT were 81.5, 96.2, and 100%, respectively; for the 412 control sera, the specificities were 99.0, 99.8, and 100%. The diagnostic efficiency (area below the receiver operating characteristic curve) of Brucellacapt was 0.987852 (95% confidence interval [CI], 0.95109 to 0.99286), very similar to the diagnostic efficiency of the Coombs test (0.97611; 95% CI, 0.94781 to 0.99146) and higher than that of SAT (0.91013; 95% CI, 0.86649 to 0.94317). The results of the Brucellacapt test were compared with those of the Coombs test (correlation coefficient, 0.956; P= 0.000) and SAT (correlation coefficient, 0.866; P = 0.000). The study shows very good correlation between the Brucellacapt and Coombs tests, with a high concordance between titers obtained in the two tests. Nevertheless, lower correlation and concordance were found between the Brucellacapt and Coombs tests when the results for titers of ≥1/160 were compared (0.692; P = 0.000). In acute brucellosis, the Brucellacapt and Coombs tests render positive titers of ≥1/160. When the titers are lower, they increase significantly in the following 30 days, despite the evolution of SAT titers. In contrast, Brucellacapt and Coombs titers are always high (≥1/640) in brucellosis with long evolution, whether SAT titers are higher or lower than 1/160.

Rose Bengal test: diagnostic yield and use for the rapid diagnosis of human brucellosis in emergency departments in endemic areas

“…The rose Bengal plate agglutination test, Wright's seroagglutination, Coombs anti‐brucella test and indirect immunofluorescence were performed as described previously [11–13]. The immunocapture‐agglutination test (Brucellacapt; Vircell SL, Santa Fé, Spain) was performed according to the manufacturer's instructions [14].…”

Rapid diagnosis of human brucellosis by SYBR Green I-based real-time PCR assay and melting curve analysis in serum samples

“…All isolates were sent to the National Brucellosis Reference Laboratory in Valladolid, Spain, for definitive identification and biotyping. The rose Bengal agglutination test and Wright's seroagglutination test were performed as described previously [14], and the immunocapture-agglutination test (Brucellacapt; Vircell SL, Sante Fé, Spain) was performed according to the manufacturer's instructions [15].…”

An old foe still with us: Troubling issues with brucellosis

“…This test is based on an immunocapture agglutination technique and detects nonagglutinating IgG and IgA antibodies, as well as agglutinating antibodies (11). Studies revealed that the specificity and sensitivity of CAT and ICAT methods were similar and, hence, both could be preferred to verify SAT (14,15). Brucella Coombs gel test is a new agglutination-based serologic test, which is practical, and yields results within 2 h. Irvem et al reported that the gel test method showed excellent correlation with both CAT and ICAT tests (16).…”