Rapid detection of Salmonella in milk by electrochemical magneto-immunosensing

A very simple and rapid method for the detection of Salmonella in milk is reported. In this approach, the bacteria are captured and preconcentrated from milk samples with magnetic beads through an immunological reaction. A second polyclonal antibody labeled with peroxidase is used as serological confirmation with electrochemical detection based on a magneto-electrode. The 'IMS/m-GEC electrochemical immunosensing' approach shows a limit of detection of 5 x 10(3) and 7.5 x 10(3) CFU mL(-1) in LB and in milk diluted 1/10 in LB broth, respectively, in 50 min without any pretreatment. If the skimmed-milk is preenriched for 6 h, the method is able to detect as low as 1.4 CFU mL(-1), while if it is preenriched for 8 h, as low as 0.108 x CFU mL(-1) (2.7 x CFU in 25 g of milk, in 5 samples of 5 mL) are detected accordingly with the legislation. Moreover, the method is able to clearly distinguish between food pathogenic bacteria such as Salmonella and Escherichia coli. The features of this approach are discussed and compared with classical culture methods. (C) 2009 Elsevier B.V. All rights reserved.