Similar drawbacks of immunoassays as a result of high viscosity of egg were reported in a previous study (Brigmon et al., 1995) when they used ELISA to detect SE in eggs. In that study, a minimum of 107 cells/ml were required for a positive reaction with 10% homogenized whole eggswhile only 104 cells/ml of SE in pure culture were necessary for ELISA detection. This suggests that the albumen and lipids in yolk may act as blocking agents inhibiting antibody–antigen binding reactions in the ELISA. Extraction of bacterial antigen from egg contents using the organic fatty acid mixture provided excellent running capability and a stronger positive signal on the test panel kit (Table 1).