Dataset Information

Genotypic Diversity among Campylobacter jejuni Isolates in a Commercial Broiler Flock.

ABSTRACT: Analysis of nucleic acid polymorphism in the flagellin genes of Campylobacter jejuni was used to investigate genetic diversity among Campylobacter spp. in a commercial broiler flock. Three hundred single colonies of C. jejuni were isolated from fecal samples collected weekly for 3 weeks immediately before slaughter. Both the flaA and flaB genes were amplified by PCR, and the PCR product was digested with the restriction enzyme AluI. The fragments generated were then analyzed by agarose gel electrophoresis. Among the 300 recovered isolates, five different restriction fragment length polymorphism profiles were observed. Three of these profiles were dominant during the course of the study, and the other two profiles were detected at low frequency. Analysis of genetic variation in C. jejuni over the course of an experimental infection lasting 7 weeks indicated that there was no obvious drift in the flagellin gene type. These findings demonstrate that a range of bacterial genotypes can constitute the bacterial population within a commercial poultry flock, with the most likely sources of these types being multiple environmental exposure and/or genetic drift within the population. This degree of diversity must be considered in epidemiological analyses which utilize genetic typing methods that investigate Campylobacter contamination of any food source, including poultry, to ensure that the total gene pool for C. jejuni is evaluated.

SUBMITTER: Thomas LM

PROVIDER: S-EPMC1389157 | biostudies-other | 1997 May

REPOSITORIES: biostudies-other

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Genotypic Diversity among Campylobacter jejuni Isolates in a Commercial Broiler Flock.

Thomas L M LM Long K A KA Good R T RT Panaccio M M Widders P R PR

Applied and environmental microbiology 19970501 5

Analysis of nucleic acid polymorphism in the flagellin genes of Campylobacter jejuni was used to investigate genetic diversity among Campylobacter spp. in a commercial broiler flock. Three hundred single colonies of C. jejuni were isolated from fecal samples collected weekly for 3 weeks immediately before slaughter. Both the flaA and flaB genes were amplified by PCR, and the PCR product was digested with the restriction enzyme AluI. The fragments generated were then analyzed by agarose gel elect ...[more]

PMID: 16535602

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Project description:Background: Campylobacter is commonly transmitted to humans from chickens. Campylobacter jejuni is the species most frequently associated with human illness, and the most prevalent species recovered from poultry. Objective: The objective of this study was to analyse a sub-population of C. jejuni from two broiler flocks on the farm and at slaughter using whole-genome sequencing to gain insights into the changes in the Campylobacter population during broiler production, including changes in virulence and antimicrobial resistance profiles. Methods: In this study, ten composite faecal samples (n=10), obtained by pooling ten fresh faecal samples (n=10), were collected in the broiler house on two farms on days 14, 21, 28, and 34 (n=80) and ten composite (n=10) caecal samples were collected at the time of slaughter for each flock (n=20). These were tested for C. jejuni using the ISO 10272-2:2016 method. Seven isolates were randomly selected from each of the nine Campylobacter-positive sampling points (n=63) and were subjected to antimicrobial susceptibility tests. Their genomes were sequenced and the data obtained was used to characterise the population structure, virulence, antimicrobial resistance determinants and inter-strain variation. Results: The Farm 1 isolates had three MLST types (ST257-257, ST814-661 and ST48-48) while those on Farm 2 were ST6209-464 and ST9401. Interestingly, only the MLST types positive for most of the virulence genes tested in this study persisted throughout the production cycle, and the detection of antimicrobial resistance determinants (gyrA T86I and tetO) increased after thinning and at slaughter, with the detection of new strains. Conclusion: The persistence of the most virulent strains detected in this study throughout the production cycle has important implications for the risk to consumers and requires further investigation. The detection of new strains within the population corresponding with the time of thinning and transportation reflects previous reports and provides further evidence that these activities pose a risk of introducing new Campylobacter strains to broiler batches.

Project description:Campylobacter jejuni is the leading cause of bacterial food-borne infection; chicken meat is its main source. C. jejuni is considered commensal in chickens based on experimental models unrepresentative of commercial production. Here we show that the paradigm of Campylobacter commensalism in the chicken is flawed. Through experimental infection of four commercial breeds of broiler chickens, we show that breed has a significant effect on C. jejuni infection and the immune response of the animals, although these factors have limited impact on the number of bacteria in chicken ceca. All breeds mounted an innate immune response. In some breeds, this response declined when interleukin-10 was expressed, consistent with regulation of the intestinal inflammatory response, and these birds remained healthy. In another breed, there was a prolonged inflammatory response, evidence of damage to gut mucosa, and diarrhea. We show that bird type has a major impact on infection biology of C. jejuni. In some breeds, infection leads to disease, and the bacterium cannot be considered a harmless commensal. These findings have implications for the welfare of chickens in commercial production where C. jejuni infection is a persistent problem. Importance: Campylobacter jejuni is the most common cause of food-borne bacterial diarrheal disease in the developed world. Chicken is the most common source of infection. C. jejuni infection of chickens had previously not been considered to cause disease, and it was thought that C. jejuni was part of the normal microbiota of birds. In this work, we show that modern rapidly growing chicken breeds used in intensive production systems have a strong inflammatory response to C. jejuni infection that can lead to diarrhea, which, in turn, leads to damage to the feet and legs on the birds due to standing on wet litter. The response and level of disease varied between breeds and is related to regulation of the inflammatory immune response. These findings challenge the paradigm that C. jejuni is a harmless commensal of chickens and that C. jejuni infection may have substantial impact on animal health and welfare in intensive poultry production:

Dataset Information

Genotypic Diversity among Campylobacter jejuni Isolates in a Commercial Broiler Flock.

Publications

Genotypic Diversity among Campylobacter jejuni Isolates in a Commercial Broiler Flock.

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