Evaluation of PCR, ELISA, and Culture Methods for the Diagnosis of Animal Brucellosis

Abstract

The present study was undertaken to evaluate polymerase chain reaction (PCR) technique in the diagnosis of brucellosis in comparison with the enzyme linked immunosorbent assay (ELISA) and microbiological culture techniques in animal’s blood and aborted fetuses. Thirty animal blood samples were used 20 of them were rose bengal plate test (RBPT) positive and which were subdivided into two groups (11) vaccinated and (9) not-vaccinated, and 10 negative controls. ِ All these samples were examined by PCR using primer pair to amplify a 223-bp region within a gene coding for 31-kDa Brucella antigen, ELISA and culture. Five aborted fetuses were also included in this study these were examined by PCR using the same mentioned pair of primers and culture only. The results of the 20 RBPT +ve blood samples revealed that 13 and 7 were also positive by PCR and ELISA representing 65% and 35% sensitivity, none was positive by culture. There was no positive case among the control group by all the tests which included in this study so its specificity were 100%. The overall agreement between PCR and ELISA and PCR and culture were 73.33% and 56.66% respectively. From the five aborted fetuses which included in this study 4 were positive for Brucella infection by PCR and 3 of the 4 were also positive by culture, one was negative by both. The overall agreement between PCR and culture was high and reached 80%. On the basis of biochemical characteristics results the two isolates which were from sheep fetuses were Brucella melitensis and one Brucella abortus isolates from aborted buffalo fetus. Due to many advantages, like speed, safety, high sensitivity and specificity, PCR is recommended to use in the diagnosis of animal brucellosis but its results need more evaluation in the vaccinated animal.