Single-step PCR for detection of Brucella melitensis from tissue and blood of goats

To overcome some of the limitations of conventional microbiological techniques in the diagnosis of brucellosis in goats, a simple single-step tissue and blood PCR, based on amplification of the 720-bp sequence of a gene coding for synthesis of an immunogenic outer membrane protein specific for Brucella melitensis (omp31), was evaluated on samples collected from 76 goats at time of slaughter. PCR results were compared with serology performed on sera from the same animals. In controlled experiments, sensitivity and specificity of tissue PCR was found to be 86 and 100%, respectively. The sensitivity of blood PCR was slightly higher (93%), with a specificity of 100%. However, both serological tests exhibited a low level of sensitivity and specificity at 71 and 86%, respectively. Since this PCR assay can be performed in 1 day, is very reproducible, easily standardized and avoids the risk of infection in laboratory workers, it will complement serological testing and be a practical and reliable tool for diagnosis of brucellosis in goats.