Protection against Staphylococcus aureus mastitis in dairy cows using a bismuth-based teat seal containing the bacteriocin, lacticin 3147.

We assessed the effectiveness of a novel dry cow treatment containing lacticin 3147 using deliberate challenge studies in lactating cows. Infection-free quarters of lactating cows were infused with Teat seal (Cross Vetpharm Group, Ltd., Dublin, Ireland) combined with the food-grade bacteriocin, lacticin 3147. Natural infection of the teat was simulated by deliberately introducing Staphylococcus aureus into the teat duct and teat sinus. Relative to control quarters, teat seal plus lacticin 3147 reduced the number of teats shedding viable cells when an inoculum of either approximately 1.7 x 10(3) or approximately 6.8 x 10(3) cfu per teat was used. In addition, the numbers of challenge organisms in those teats from which S. aureus was subsequently recovered were also reduced. However, when the concentration of bacteriocin in the teat seal formulation was reduced by approximately 50%, the number of teats shedding S. aureus cells was not reduced. These data indicate the potential for lacticin 3147 to prevent staphylococcal mastitis infections when a sufficient concentration of the bacteriocin is present. This study also highlights the application of a lactating-cow model to assess the effectiveness of antimicrobial intramammary products on mastitic cell populations.