Detection of staphylococcal enterotoxin B in milk and milk products using immunodiagnostic lateral flow devices

Staphylococcal enterotoxin B (SEB) is an extracellular pyrotoxin produced by Staphylococcus aureus, a known etiologic agent of food poisoning in humans. Lateral flow immunochromatographic devices (LFDs) designed for the environmental detection of SEB were adapted for use in this study to detect SEB in milk containing 2% fat, chocolate-flavored milk, and milk-derived products such as yogurt, infant formula, and ice cream. The advantage of using LFDs in these particular food products was its ease and speed of use with no additional extraction methods needed. No false positives were observed with any of the products used in this study. Dilution of the samples overcame the Hook effect and permitted capillary flow into the membrane. Thus, semisolid products such as ice cream and some yogurts, and products containing thickeners needed to be diluted using a phosphate-buffered saline-based buffer, pH 7.2. SEB was easily detected at concentrations of 5 microg/mL and 500 ng/mL when the LFDs were used. SEB was also reliably detected at concentrations below 5 and 0.25 ng/mL, which may induce serious disease.