ACCURACY OF A MULTIPLEX PCR PROTOCOL FOR Staphylococcus aureus, Streptococcus agalactiae AND Escherichia coli DETECTION IN BULK TANKS

The objective of the present study was to evaluate the accuracy of a multiplex PCR (mPCR) protocol for Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli detection in bovine milk samples collected from bulk tanks. Twenty dairy farms in mid-west of Sao Paulo State, Brazil were enrolled. Milk samples collected from each bulk tank were evaluated by mPCR and microbiological culture (gold standard test). S. aureus , S. agalactiae and E. coli were isolated by culture in 30%, 10% and 40% respectively, and detected by mPCR in 0%, 10% and 35% bulk tank milk samples respectively. mPCR has demonstrated 93.2% specificity and 37.5% sensitivity values, with 78.3% accuracy. It was possible to conclude that this mPCR protocol was efficient for S. agalactiae and E. coli detection in the evaluated bulk tank milk samples, but failed to detect S. aureus . Despite the high specificity values obtained by mPCR, the sensitivity levels were low, indicating that this molecular method should only be recommended as a complementary diagnosis test for milk quality monitoring in bulk tanks.