DETECTION OF STAPHYLOCOCCUS-AUREUS IN BULK TANK MILK USING MODIFIED BAIRD-PARKER CULTURE MEDIA

The purpose of this project was to evaluate the use of 2 selective/dif ferential culture media for detecting Staphylococcus aureus in bulk ta nk milk. One medium was Baird-Parker agar base supplemented with egg y olk tellurite emulsion and acriflavine. The other medium was Baird-Par ker agar base supplemented with rabbit plasma/bovine fibrinogen and ac riflavine. An increased inoculum of bulk tank milk (0.3 mL) was used t o enhance the detection of S. aureus in samples containing low numbers of organisms, The sensitivity and specificity for detecting S. aureus in bulk tank milk were 94.8% and 100%, respectively, using Baird-Park er agar base supplemented with egg yolk tellurite emulsion and acrifla vine, and 89.7% and 100%, respectively, using Baird-Parker agar base s upplemented with rabbit plasma/bovine fibrinogen and acriflavine. Both media are practical for detecting S. aureus in bulk tank milk and mon itoring its spread in lactating dairy herds in Alberta.