Detection of Brucella Associated with Bovine Abortions in an Organized Dairy Farm

Abstract

The Brucella abortus is an important bacterial pathogen responsible for reproductive losses in cattle and buffaloes. In females, the disease is manifested as late-term abortion (commonly during the last trimester), retained placenta, reduced fertility and repeat breeding or even stillbirths or birth of weak calves. The present study screened a total of 12 abortion-associated samples, including blood, placental tissues, and foetal stomach contents, from both cattle and buffaloes from an organized dairy farm in Punjab. Serum samples were screened for Brucella antibodies using the Rose Bengal Plate Test (RBPT) and the placental and foetal samples were subjected to bacterial isolation. Genomic DNA extracted directly from clinical samples and from culture isolates was subjected to genus-specific PCR targeting the bcsp31 gene. Samples positive by genus-specific PCR were further characterized using Bruce-ladder multiplex PCR. Of the 12 serum samples tested, 7 were positive by RBPT. Direct genus-specific PCR detected Brucella DNA in 11 samples, yielding the expected 223-bp amplicon. Four Brucella isolates were successfully recovered through culture and subsequently confirmed by genus specific PCR. Bruce-ladder multiplex PCR confirmed all genus-specific PCR-positive samples as Brucella abortus, producing characteristic amplicons of 152, 450, 587, 794, and 1682 bp. The detection of Brucella abortus in aborted samples from cattle and buffaloes through serological, molecular, and bacteriological methods underscores the importance of an integrated diagnostic approach for accurate diagnosis and effective control of brucellosis.