Developing a fluorescent latex microparticle immunoassay using Alexa Fluor 568 for detection of staphylococcal enterotoxin A.

摘要

Staphylococcus aureus produces heat-stable toxins that cause major foodborne gastroenteritis. Staphylococcal enterotoxin A (SEA) is the most recovered toxin in staphylococcal food poisoning outbreaks. A sensitive method for the detection of SEA is needed for food safety and food defense monitoring. The objectives of this study were to develop a fluorescent immunoassay for the detection of SEA below the toxic level of 1 ng/mL and to minimize sample preparation. An affinity-purified anti-SEA was covalently linked to polystyrene microparticles. The SEA toxin was labeled with Alexa Fluor 568 (A568). The concentrations of these reagents were optimized for the detection of SEA in buffer and spiked hotdogs. SEA in samples was captured by the anti-SEA linked to the latex, followed by the binding of the SEA-A568 tracer. The latex-anti-SEA complex, bound with SEA and SEA-A568, was separated by centrifugation, and the fluorescent density of the supernatant was measured. SEA was detected at 0.25-10 ng/mL in buffer and in spiked hotdogs (ng/g). This fluorescent latex particle immunoassay can be utilized for the detection of SEA in a multitoxin detection system..