STAPHYLOCOCCUS-AUREUS MASTITIS .2. DIAGNOSTIC ACIDS, THERAPY, AND CONTROL

The low, intermittent shedding of Staphylococcus aureus organisms in the milk of infected cows can result in the absence of the organisms during routine culturing of bulk-tank milk. Although cows that are infected with S. aureus can be identified by enzyme-linked immunosorbent assay, the test is better at identifying noninfected cows. Culturing the milk is the best method of identifying infected cows, but not all such cows can be singled out by this method. The production of beta-lactamase, bacterial L forms, and phagocytic intracellular location are characteristics of S. aureus that make it resistant to therapy. The cure rate is greater for dry-cow therapy than for lactation therapy. Correct milking techniques, functioning equipment, dry-cow antibiotic therapy, germicidal teat dipping, culturing of herd replacements, and culling of chronically infected cows are the major components in controlling S. aureus in herds.