Immunomagnetic separation methods for the isolation of Campylobacter jejuni from ground poultry meats

Campylobacter jejuni is now recognized as a leading foodborne pathogen, for which poultry products constitute the main transmission route. Two alternative immunomagnetic beads (IMB) were tested for direct detection of C. jejuni ATCC 35918 in artificially inoculated ground poultry meats and culture suspension. Polyclonal anti-Campylobacter antibodies were used to coat tosylactivated Dynabeads. The same antibodies conjugated with biotin were used to label streptavidin-coated beads. After these beads were incubated with inoculated poultry slurry or culture suspension, Campylobacter-bead complexes were separated from other components with a magnet. The capture efficiency was tested by plating bead-captured cells and unbound cells in the supernatant onto Karmali agar. The effects of different coating procedures, incubation time (60, 90, 120 min), numbers of immunomagnetic beads (10(6) to 10(7)/ml) and innoculum levels (10(3) to 10(7) CFU/g or ml) were determined. Without pre-enrichment, this approach could detect 10(4) CFU/g of ground poultry meats. These methods represent a new approach to extracting, concentrating and isolating Campylobacter spp. directly from foods.