Detection of Campylobacter jejuni in poultry samples using an enzyme-linked immunoassay coupled with an enzyme electrode

An enzyme-linked immunoassay coupled with a tyrosinase modified enzyme electrode was used for rapid detection of Campylobacter jejuni. The immunomagnetic separation (IMS) method was investigated to achieve optimal isolation of C. jejuni cells. Eight types of beads with three different sizes and function groups were coated with anti-C. jejuni to isolate C. jejuni from the sample solution. Bead size and coating methods were found to be major factors that influenced the capture efficacy. Streptavidin-labeled beads (2.8 μm) provided the greatest capture ability. Three blocking reagents were tested to minimize non-specific binding. Bovine serum albumin (BSA) showed the best blocking capability. Two IMS formats were tested. Competitive immunoassay cut the detection time to 1.5 h, but the detection limit was relatively high (10⁶ CFU/ml). This system was evaluated using C. jejuni pure culture and poultry samples inoculated with C. jejuni. This detection method for C. jejuni could be completed within 2.5 h and had a detection limit of 2.1×10⁴ CFU/ml. No significant difference was found between pure culture samples and poultry samples (P>0.01). A linear relationship was found between C. jejuni cell numbers and the peak current ratio in a range of 10²–10⁷ CFU/ml (R²=0.94).