Transmission dynamics of ESBL/AmpC-producing E. coli on a broiler farm

P.M.C. Huijbers, A.H.A.M. van Hoek, M. de Jong, E. van Duijkeren

Research output: Chapter in Book/Report/Conference proceedingAbstract

Abstract

Background Transmission of ESBL/AmpC-producing E. coli between broilers and humans resulting from close contact between humans, broilers and their environment on farms has been suggested. To further elucidate the role of broilers in the carriage of these bacteria among humans, more information on farm transmission dynamics is necessary. The aim of this study was to quantify transmission rates and routes within an organic broiler flock, and to determine whether carriage of ESBL/AmpC-producing E. coli is persistent in broilers. Methods A longitudinal study was conducted on an organic broiler farm. Eighty broilers were randomly selected and tagged for individual tracking. Cloaca swabs from these broilers, 20 randomly chosen untagged broilers, and 11 environmental samples from the broiler house were taken seven times from arrival on the farm to slaughter age (day 1, 3, 4, 7, 10, 42, and 70). ESBL/AmpC-producing E. coli were isolated by selective enrichment and culture on selective plates. ESBL/AmpC-production was confirmed by combination disc diffusion test. At each sampling time the prevalence of positive broilers and environmental samples was calculated. Information about the ESBL/AmpC-status of tagged broilers, randomly chosen broilers, and environmental samples at each sampling time was combined to calculate the transmission rate parameter and the reproduction ratio (R0) using a susceptible-infectious-susceptible (SIS) model. Results The prevalence of ESBL/AmpC-producing E. coli on day 1 of the production round was 28.8% (95%CI 19.2-40.0%) in tagged broilers, and 45.5% (16.8-76.6%) in environmental samples. After 3 days, almost 100% of broiler and environmental samples were positive, which is indicative of the rapid transmission of these bacteria in the broiler house. Preliminary analysis of the R0 indicates that this is significantly larger than 1, indicating that ESBL/AmpC-producing E. coli are able to transmit and persist in broiler flocks. Carriage was intermittent in all broilers, except one who was positive at all sampling times. At the end of the production round, 39.4% (95%CI 27.6-52.2%) of tagged broilers, and 27.3% (95%CI 6.0-61.0%) of environmental samples were contaminated with ESBL/AmpC-producing E. coli, indicating that these bacteria could enter the food chain. Conclusions This study shows that ESBL/AmpC-producing E. coli are able to transmit and persist in broiler flocks in the absence of antimicrobials, resulting in an endemic situation. Ongoing molecular characterisation of broiler and environmental isolates will yield important information about the contribution of different routes in the transmission of ESBL/AmpC-producing E. coli on broiler farms and provide a basis for intervention.
Original languageEnglish
Title of host publicationProceedings of the 3rd International One Health Congress,
Publication statusPublished - 2015
Event3rd International One Health Congress, Amsterdam, The Netherlands -
Duration: 15 Mar 201518 Mar 2015

Conference

Conference3rd International One Health Congress, Amsterdam, The Netherlands
Period15/03/1518/03/15

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