Development of an indirect competitive ELISA for detection ofCampylobacter jejuni subsp.jejuni O:23 in foods

An indirect enzyme immunoassay for rapid detection ofCampylobacter jejuni subsp.jejuni O:23 has been developed. Optimum concentrations of immobilized cells, polyclonal chicken IgY, and rabbit anti-IgY antibody-horseradish peroxidase conjugate were 3.1 CFU/nL, 10 µg/mL, and 8 µg/mL, respectively. Under such conditions, the detection limit reached 50 CFU/µL, limit of quantification being 480 CFU/µL. By testing 5 chromogens.viz. 1,2-benzenediamine, 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid), 3,3′,5,5′-tetramethylbenzidine, bi(4,4′-anisidine) and 3-methyl-2-benzothiazolinone hydrazone, in horseradish peroxidase substrate, 1,2-benzenediamine or 3,3′,5,5′-tetramethylbenzidine as H-donors in the enzyme substrate provided the highest ELISA sensitivity. The applied polyclonal antibody was specific for homogeneous antigen. The cross-reactions were observed only with one strain ofC. sputorum subsp.sputorum (21.5 %) and with G+ bacteriumMicrococcus luteus (6.1 %). Preliminary tests have been performed with a limited number of artificially contaminated food samples. No matrix effects on the ELISA sensitivity were observed. The results (by means of ELISA) were comparable with those given by both a standard cultivation method performed according toČSN ISO 10272 and commercially available Singlepath® Campylobacter GLISA-Rapid Test.