Staphylococcus aureus is a common udder pathogen in dairy cows, and cause severe mastitis problems in some herds in Egypt. In herds where normal control measures are not successful, vaccination might be an additional tool to use if sufficiently efficient. In the last years the knowledges on cow mastitis are remarkably improving, nevertheless the attention has been never focused on vaccination as preventive strategy for the control of mastitis. A, successful Staphylococcus aureus vaccine should elicit a long-term antibody response that prevents establishment of the infection. As sera of immunized pregnant heifers with S. aureus lysed cells formulated with a classical adjuvant stimulate antibodies production that inhibited internalization in mammary epithelial cells (MEC) and increased phagocytosis by milk macrophages, the aim of the present study was to evaluate the humoral immunological response to a commercially available vaccine. (Lysigin™, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO) and its potential use as a preventive way for S. aureus mastitis in
Holstein cows Vaccinated (V) and not vaccinated (N-V) groups, of 30 cows, were selected from one herd of the same farm. The herd received a double vaccination (Lysigin™), 30 and 15 days before calving, and 5 months after calving) In conclusion, the current study on commercially available vaccine (Lysigin™), and its potential use as a preventive way for
S. aureus mastitis in Holstein cows in Egypt showed encouraging results associated with  induction of specific and significant antibody responses and significant lower prevalence and incidence of clinical, subclinical and repeated mastitis. The vaccine is considered an additional tool in the control of S. aureus infections on farms and that its use should be
always associated with excellent farm management practices to successfully improve the infections control within the herd.