Magnetic counter for Group B streptococcus detection in milk.

Identification of bovine mastitis pathogens is nece ssary to control the disease, reduce the risk of ch ronic infections and target the antimicrobial therapy to be prescribed. Development prospects for new bovine mastitis diagnosis method ologies go also through technological advances for high sensitivity and spe cificity, rapid and efficient devices that can offe r a “cow-side” use, meaning that raw milk collected for analysis should have limited pre -treatment. This work aims at developing a magnetic counter that identifies and quantifies Streptococcus agalactiae (a Group B streptococci) in raw milk. Functionaliz ed 50 nm magnetic beads with rabbit anti- Streptococcus B polyclonal antibody (8453-2000 AbD Serotec) were used for dynamic magnetic detection. This detection approach involved the application of a magnetic field perpen dicular to the sensors in order to magnetize the ma gnetically labelled bacterial cells as they pass over the sensor, so they generate a de tectable fringe field. The optimized flow rate used (50 μl/min) allows the achievement of that bacterial cell’s magnetic signal. This micr ofluidic device also allows milk running without br idging the channels. This work proposes a technique to detect directly Streptococcus agalactiae cells in milk samples without the need of sample t reatment.