Campylobacter jejuni is a commensal microorganism of the poultry
gastrointestinal tract. Broilers, layers, ducks, turkeys, and quails can be colonized by
Campylobacter without illness occurring. The vast majority of human Campylobacter
infections are recognized as being foodborne. For 2008, preliminary FoodNet data
showed that the Campylobacter incidence of infection, 12.68 per 100,000 of the U.S.
population, is the second highest, only behind Salmonella at 16.20 per 100,000. To
further understand Campylobacter’s role as a foodborne pathogen, analysis at the
molecular level is needed.
Microbial molecular typing allows for identification and differentiation of
bacterial strains beneath the species level. In this study, the “gold standard” method for
molecular subtyping, Pulsed Field Gel Electrophoresis (PFGE), along with Diversilab®
repetitive element Polymerase Chain Reaction (rep-PCR) and 16S-23S Internal Spacer
Region Denaturing Gradient Gel Electrophoresis (ISR DGGE) were used for the
molecular typing of Campylobacter jejuni isolates obtained during different stages of
commercial broiler production and processing. In addition, the C. jejuni isolates were tested for resistance to antimicrobials commonly used in both veterinary and human
medicine. Antimicrobial resistance testing was carried out using a broth dilution system.
The majority of recovered isolates came from post-harvest carcass rinsates. Carcass
rinses were obtained at post-evisceration, post-chill stages. All isolates (n = 46) were
identified by the Polymerase Chain Reaction as Campylobacter jejuni. Three genotypes
(n = 44, n = 1, n = 1) were identified by PFGE. The 46 rep-PCR products grouped into
seven clusters and two outliers. Clustering of rep-PCR products by sample source was
not observed. No relatedness trends were observed for isolates recovered from the same
source. The combination of PFGE and Diversilab rep-PCR methods provides highly
discriminatory molecular typing results.
These results provide practical epidemiological information that shows postevisceration
and post-chill stages are still important targets for intervention studies. The
very high occurrence of C. jejuni isolates exhibiting genotype A suggests it may
differentially express certain gene(s) that enable this strain to more favorably survive
under the different harsh environmental conditions encountered during production and
processing.
In addition, phenotypic testing revealed all of the isolates were not resistant to
the antimicrobials azithromycin, ciprofloxacin, erythromycin, gentamycin, tetracycline,
florfenicol, nalidixic acid, telithromycin, and clindamycin at any of the concentrations
tested. All the C. jejuni isolates exhibited an indistinguishable two-band 16S-23S ISR
DGGE profile. Overall, these C. jejuni commercial broiler pre- and post-harvest isolates
exhibited an extremely low degree of molecular and phenotypic variability.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-12-8643 |
| Date | 2010 December 1900 |
| Creators | Hernandez, Charles Andrew |
| Contributors | Caldwell, David J. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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