Immunosensing system for rapid multiplex detection of mastitis-causing pathogens in milk

Mastitis, an inflammation of the mammary gland and udder tissue, is the major endemic disease of dairy cattle. In addition to causing health problems to the animals, mastitis leads to the reduction of milk production and quality, representing a significant economic burden for farmers. To enable timely treatment of infected animals with pathogen-specific antibiotics, the development of automated analytical methods for rapid on-site identification and quantification of mastitis-causing pathogens in milk is particularly important. An immunosensing system for multiplex detection of the two most common mastitis-causing pathogens Staphylococcus aureus and Escherichia coli is proposed in the present study. This immunosensor combines Bead Injection Analysis (BIA), attachment of pathogens onto renewable micro-column, biorecognition of bound pathogens by specific antibodies, conjugated with different fluorescence markers and the measurement of fluorescence signals. The analysis takes 20min and exhibits detection limits of < 50 CFU mL^-1 for E. coli and 100 CFU mL^-1 for S. aureus in milk. The applicability of the immunosensor was demonstrated by analyzing milk samples from cows, who were suffering from acute clinical mastitis.