Molecular typing of Brucella species in dairy farms in the Province of Azuay – Ecuador

Brucellosis is a worldwide zoonotic disease in cattle, caused mainly by Brucella abortus previously reported in certain regions of Ecuador. The characterization of circulating strains of B. abortus in dairy herds is vital to understand the epidemiology of this disease. The bacteriological typing is a slow, risky process and requires specialized laboratories for Brucella spp. The aim of this study was to type the strains of Brucella spp. that affect bovines in the Province of Azuay, through molecular assays, from blood and milk samples from cows seropositive to brucellosis. In farms seropositive to ELISA-Indirect in milk, 70 Holstein crossbred cows were selected, individually reacting to the Rose Bengal tests and confirmed with competitive ELISA. The DNA was extracted from these blood and milk samples, initially verifying the viability of the bovine genetic material with specific oligonucleotides for the Bos genus. The DNA amplification for Brucella spp. It was performed by PCR-AMOS with genus primers for the IS711 region and Species primers for Brucella abortus, Brucella mellitensis, Brucella suis and Brucella ovis. Bos DNA could be identified in 65 (92.8%) milk samples and in 62 (88.5%) blood samples. A total of 62 (95.4%) DNA samples extracted from milk were positive for the genus Brucella spp. All blood samples were negative. The PCR-AMOS showed bands with a molecular weight of 498 base pairs in samples from four animals corresponding to B. abortus. This is the first study of molecular identification in the Province of Azuay with scientific evidence of the species of Brucella spp. circulating in the herds of the area, serving as a basis for the future identification of B. abortus biovars not yet reported in this area of the Country.