A DIFFERENTIAL-SELECTIVE MEDIUM AND DRY ICE-GENERATED ATMOSPHERE FOR RECOVERY OF CAMPYLOBACTER-JEJUNI

A selective-differential medium for isolation of Campylobacter jejuni from chicken carcasses was developed. The medium, Campy-Cefex, consisted of Brucella agar, 5% lysed horse blood, 0.05% ferrous sulfate (FeSO4.7H2O), 0.05% sodium pyruvate, 0.02% sodium bisulfite, and antibiotic supplements of 33 mg/L sodium cefoperazone and 200 mg/L cycloheximide. A total of 41 chicken carcass samples were plated onto Campy-Cefex, Campylobacter cefoperazone desoxycholate agar, and Campylobacter brucella agar plate media. Campy-Cefex proved as productive and selective as the other media. Campy-Cefex allowed for easier differentiation of C. jejuni from other flora compared to differentiation on Campylobacter cefoperazone desoxycholate agar medium. Differentiation of the non-Campylobacter spp. flora from Campylobacter spp. was the same on both Campy-Cefex and Campy-BAP. The selectivity for the organism on Campy-Cefex was better than on Campy-BAP. Growth of seven isolates of C. jejuni in microaerobic-(5% O2, 10% CO2, 85% N2) and dry ice-generated atmospheres was also assessed. After 24 h of incubation, the mean log10 CFU generated, using the same culture suspensions and medium, was 2.07 and 1.81 for the microaerobic and dry ice atmospheres. respectively. These two developments allow for simplification of materials and methods required to isolate C. jejuni from foods.