A blood-free enrichment medium for growing Campylobacter spp. under aerobic conditions

Detection limits for Campylobacter jejuni strains JH93 and ATCC 29428 in a new blood-free enrichment broth (BFEB) were investigated under aerobic conditions. Cultures of Camp. jejuni were inoculated into 50 ml BFEB containing 10% food homogenate in 50 ml screw-cap tubes. After 24 h enrichment under aerobic conditions, Camp. jejuni were isolated on four selective agar media. The least squares means of the detection limit 50% endpoint (DL50) values were 0.4 (plain BFEB), 0.9 (crabmeat), 1.7 (mushroom), 1.7 (raw milk) and 2.1 (oyster) colony forming units (cfu) 5 g-1 food. The efficiency of the BFEB was significantly affected (P < 0.05) by food type and bacterial strain. Overall, the BFEB enrichment compared favourably with the existing US Food and Drug Administration method under modified atmosphere. In addition, the BFEB method did not require the use of blood, special equipment or Oxyrase to reduce oxygen tensions.