Reliably colonising broiler chickens with spp. using a litter-based method.

1. Chicken-associated spp. are the cause of most food poisoning cases in Europe. In order to study the host-pathogen interactions, a reliable and reproducible method of colonising chickens with the bacteria is required. 2. This study aimed to identify a more appropriate and less invasive method of colonisation (cf. gavaging) by seeding bedding material (litter) that commercial chickens are kept on with a mixture of spp., broth and faeces. 3. The first phase of the study tested the longevity of spp. recovery in seeded litter over 24 h: significantly more spp. was recovered at 0 or 3 h post-seeding than at 6 and 24 h post-seeding, indicating that the pathogen can survive to detectable levels for at least 3 h in this environment. 4. In the second phase, three groups of 10 broiler chickens (negative for spp. prior to exposure) were exposed at 21 days of age to one of three different and mixes (A, B, C), using the method above. At 28 days of age, birds were euthanised by overdose of barbiturate or cervical dislocation, and livers and caeca removed for spp. assessment. 5. All liver and 28/30 caeca samples tested positive for spp., with mix A and C giving higher counts in the caeca than mix B. The method of euthanasia did not affect spp. counts. 6. In conclusion, a successful method for reliably colonising broiler chickens with spp. has been developed which negates the need for gavaging and is more representative of how contamination occurs in the field.