Microbiological and molecular analysis of mastitis in dairy cows

Abstract

Milk is an essential food for human and animal nutrition, whose biological and economic value is compromised by diseases such as bovine mastitis, one of the main causes of economic losses in dairy production. This study evaluated the presence of mastitis in milking cows under a semi-intensive management system using a microbiological and molecular approach. One hundred cows with symptoms of clinical and subclinical mastitis were analyzed. Staphylococcus aureus was isolated using Baird-Parker agar, Gram staining, and catalase testing. Molecular confirmation was performed by PCR targeting the nucA and femB genes. Ninety-two point five percent of the isolates corresponded to Gram-positive cocci, ruling out contamination by Gram-negative bacilli and suggesting a specific etiology of mastitis. Amplification of the femB gene produced specific bands (650 bp), confirming the presence of Staphylococcus aureus, while the nucA gene presented nonspecific results, highlighting the need to optimize PCR conditions to improve detection specificity, in addition to implementing control methods, such as the California test, to detect early and control the spread of Staphylococcus aureus, which would benefit dairy production.