Simultaneous quantitative analysis of Listeria monocytogenes and Staphylococcus aureus based on antibiotic-introduced lateral flow immunoassay

Food poisoning caused by microorganisms has caused widespread concern. Herein, a highly sensitive on-site screening test strip for the detection of different pathogenic microorganisms (Listeria monocytogenes and Staphylococcus aureus) was designed. In this analysis platform, colloidal gold-coupled vancomycin was used as a signal unit to label Gram-positive bacteria, and highly sensitive polyclonal antibodies were used as recognition molecules to capture these specific strains. Compared with the traditional dual-antibody sandwich model, this new type of antibiotic-pathogen-antibody sandwich model is low-cost and can simultaneously detect multiple microorganisms. Under optimal conditions, this strategy showed satisfactory sensitivity and a wide linear range (L. monocy and S. aure could be directly assayed within linear ranges of 5 × 104 to 107 and 5 × 102 to 107 CFU mL-1, and the visual detection limits were 105 and 103 CFU mL-1, respectively). The analytical performance and practicability of this sensor system have been further studied. This developed biosensor was applied to bacteria-contaminated water, milk and broth with satisfactory results. All of these attractive characteristics make the assay possess potential applications in food safety, medical diagnosis and environmental monitoring.