Campylobacter Colonization in Turkey Flocks Reared in North Carolina
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Date
2003-07-11
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Abstract
Campylobacter spp are currently the leading cause of foodborne acute bacterial gastroenteritis in people in industrialized countries. It is estimated by the Centers for Disease Control and Prevention that Campylobacter accounts for 2.4 million human cases of gastroenteritis annually in the United States. The main risk for acquiring Campylobacter infection is handling raw poultry and/or consumption of undercooked meat of animal origin, particularly poultry. Research concerning Campylobacter in poultry has been focused on broilers; little information is available on the colonization of turkeys. Consumption of turkey products has increased considerably in recent years; therefore, there is a need to focus attention on this potential vehicle of campylobacteriosis.
First, a longitudinal study was conducted on two pairs of sibling turkey flocks obtained from the same hatch that shared a common breeder source. One flock from each pair was raised commercially whereas the other was raised under contract at the Teaching Animal Unit (TAU) at the North Carolina State University Veterinary School. Time of placement, feed formulations, and bird density were the same among the members of each pair. At the completion of the production cycle, birds of each flock were processed in commercial processing plants, following standard feed withdrawal and transport protocols. Both commercial flocks became colonized at 2 to 3 weeks of age and remained colonized through processing while the flocks raised at the TAU remained free of Campylobacter until processing.
In addition to prevalence of Campylobacter spp. other epidemiological factors of interest in this study were antibiotic resistance profiles, species colonizing the birds, and strain types present throughout the life of the birds. The turkeys were predominantly colonized by C. coli (84-88%) with C. jejuni accounting for the remainder of the isolates. Both commercial flocks were colonized by a limited number of strains with one dominant strain being isolated throughout the life of the bird. C. coli isolates were resistant to a variety of antibiotics including erythromycin and fluoroquinolones. C. jejuni isolates were also resistant, but were more likely to be sensitive to erythromycin and fluoroquinolones.
These results indicate that vertical transmission, if occurring, was not sufficient for colonization of these turkey flocks by Campylobacter and points towards the important role of flock management in preventing colonization. In addition, the turkeys were colonized by one main strain type which could be due to selective pressures related to antibiotic treatments. The level of antibiotic resistance in both the C. coli and C. jejuni isolates is of definite food safety concern.
The high prevalence of C. coli in the turkeys was unexpected and developed an interest in evaluating broilers raised in the same geographical region to determine if they also were predominantly colonized by C. coli. A cross-sectional survey was conducted on 32 farms from 2 broiler integrators in the same region. Sixteen of 32 farms had flocks that were colonized with Campylobacter at 4 weeks of age. Of these 16 flocks, 10 were primarily colonized by C. jejuni whereas 5 flocks were predominantly colonized by C. coli. No samples could be purified from one of the Campylobacter-positive flocks. There was a high level of resistance in both the C. jejuni and C. coli isolates to several antibiotics including those that are used to treat human illnesses. Resistance to multiple antibiotics was more common in the turkey isolates. However, fluoroquinolone resistance was more prevalent in the broiler isolates. These findings indicate that broilers in eastern North Carolina were primarily colonized by C. jejuni and that the high prevalence of C. coli colonization that we observed in the commercial turkey flocks that we studied was likely not related to the specific geographic region. A possible explanation for the prevalence of C. coli in the turkeys is that integrators in North Carolina often raise turkeys as well as hogs, which are typically colonized by C. coli. This is not a common practice for broiler integrators. Thus, the prevalence of C. coli in turkeys is more likely to be dependent upon practices within the turkey industry in N. Carolina rather than geographic region.
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Keywords
Campylobacter Colonization, antibiotic resistance, strain typing
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Degree
MS
Discipline
Food Science
