Diagnosis and characteristics of contagious mastitis caused by Staphylococcus aureus and Streptococcus agalactiae

With rapidly increasing herd sizes, focus on contagious udder pathogens becomes important. Based on a yearly test of bulk tank milk in Danish dairy herds, the prevalence of herds infected with Streptococcus agalactiae (S. agalactiae) increased from 2 % in 2000 to 7 % in 2010, while approximately 90 % of the herds were positive for Staphylococcus aureus (S. aureus) (Katholm, et al., 2012). The reemergence of S. agalactiae raises concerns. Early and valid diagnosis is necessary to control the spread of contagious mastitis pathogens within herds. Since 2009 the real-time PathoProofTM Mastitis PCR Assay is routinely used, mainly on composite samples taken non-aseptically at milk recording from individual cows pre dry-off or from whole herd screenings.