Molecular Testing of Milk: Interpretation and Applicationin Austr

摘要

Our work focussed primarily on Streptococcus agalactiae and Mycoplasma bovis. At this stage, we do not consider that results for other organisms currently targeted by the Pathoproof~(TM) PCR are useful in assisting mastitis control in Australian dairyherds, with the possible exception of positive results for Staphyloccus aureus when buying cows. Under normal Australian milking practices, bulk tank milk samples can be assessed for the presence of Strep, agalactiae and Mycoplasma bovis using the described Polymerase Chain Reaction (PCR) test. However, our results do not indicate that herd-level diagnostic sensitivity is 100% in herds of any size.At a cycle threshold (Ct) cutpoint of 30, herd-level sensitivity of the PathoProof~(TM) PCR for Streptococcus agalactiae is probably around 86% and herd-level specificity is probably between 95% and 99%. While these values are usefully high, the fact that both values are less than 100% has important implications for the application and interpretation of the PCR test for Streptococcus agalactiae.