Comparative Assessment of Sensitivity and Specificity of Rose Bengal Test and Modified In-house ELISA by using IS711 TaqMan Real Time PCR Assay as a Gold Standard for the Diagnosis of Bovine Brucellosis

Abstract

Serological approaches such as Rose Bengal Test (RBT) and enzyme linked immunosorbent assay (ELISA) are common tests, however they are generally not sensitive or specific enough for diagnosis of Brucella because of cross-reactivity with different bacterial antigens. The work objected to evaluate the sensitivity and specificity of rose Bengal and modified in-house ELISA using IS711 real time PCR as a gold test to detect Brucella in calves sera. Two hundred and thirty (n=230) blood samples were collected from (2-3) years asymptomatic male calves in two Egyptian abattoirs. Rose Bengal test (RBT) and modified in-house ELISA were applied to determine the seroprevalence of brucellosis in abattoirs animals while quantitative Taqman real-time PCRs (RT-PCR) were implemented for the identification of Brucella genus. The overall prevalence of brucellosis was (53.9 %), (75.2 %) and (79.1 %) as determined by ELISA,RBT and RT- PCR assays respectively. Regarding statistical analysis of the reported data and considering real time PCR the gold standard, the RBT recorded a sensitivity of (79.12%) and a specificity of (39.58 %) with an accuracy of (70.87%). While (83.24%) was reported as positive predictive value and (33.33 %) as a negative predictive value. The sensitivity and specificity of ELISA were (55.49%) and (52.08 %) respectively while the accuracy was (54.78%). Positive predictive value and negative predictive value for ELISA were determined as (81.45%) and (23.58 %) respectively. RBT can be routinely used for diagnosis of Brucella as cost effective , more sensitive and accurate test than ELISA However, real time PCR is highly recommend as gold test for identification and differentiation of bovine brucellosis.