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Tracking, Quantifying, Phenotyping and Genotyping of Campylobacter in Cattle and Pigs across the Farm to Fork Continuum

Abley, Melanie J.

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Veterinary Preventive Medicine.
Salmonella and Campylobacter cause a significant number of illnesses annually in the United States and around the world, most of which are food-related. Cattle and swine can be asymptomatic carriers of both of these pathogens. We first compared estimates of Salmonella and Campylobacter concentrations using most probable number (MPN) method, direct dilution, and quantitative real-time PCR (QPCR) in spiked fecal, hide, carcass, and meat samples from cattle and swine. Different sample types were spiked with known concentrations of Salmonella enterica, Campylobacter jejuni and Campylobacter coli. Salmonella MPN results indicated there was a strong positive correlation between pre- and post-spiking concentrations for the MPN results from the bovine, and porcine, fecal samples, Campylobacter direct dilution revealed only the bovine feces for C. coli was significant for a strong positive correlation between initial spiking concentrations and post spiking values, and Campylobacter MPN results indicated there was a strong positive correlation between the pre and post spiked samples for carcass and ground beef samples. We next investigated the association between the concentration of Salmonella and Campylobacter pre- and post-harvest in cattle. Samples were collected from each of 98 individually identified cattle during the peri-harvest and post-harvest periodincluding: on farm (fecal sample), post-stunning and exsanguination (hide sponge and pre-fecal sample (lairage), pre-chilling (carcass sponge) and final product (ground meat). Salmonella and Campylobacter were cultured and quantified at each stage by using the direct dilution and most probable number method. Salmonella was not isolated from any sample, and there were no associations between Campylobacter concentrations for any sample types. We further investigated the same potential association between the concentration of Salmonella and Campylobacter pre- and post-harvest in swine. In this study, Salmonella was isolated from only two samples, but again there was no association between the isolation of Campylobacter on meat and the isolation of Campylobacter at any peri-harvest stage. Our next step was to compare the concentration of Campylobacter measured by QPCR compared to direct dilution or MPN from 100 swine (5 sample types) and 98 cattle (5 sample types). These results suggest that quantitative culture (direct dilution and MPN) would be the most appropriate means of quantifying Campylobacter in cattle and swine samples. This was based on the observation that there was no agreement between the two methods and each of the positive samples for MPN or direct dilution were PCR confirmed thus it appears that the QPCR was producing false negatives suggesting inadequate sensitivity Finally, we investigated the clonal relatedness of Campylobacter coli from pigs on farm and at processing. We completed antimicrobial susceptibility testing and multi-locus sequence typing (MLST) of these 47 isolates. Campylobacter isolates from farm, lairage, hide and carcass showed similar phenotypes and belonged to the same clonal groups based on MLST. Five new Sequence Types were identified (ST-4083, ST-4084, ST-4085, ST-4086, ST-4087). Our results indicated a high diversity of C. coli within one farm, and that meat products were contaminated with the same STs as those recovered in earlier stages of the harvest process.
Thomas Wittum (Advisor)
Julie Funk (Committee Member)
Wondwossen Gebreyes (Committee Member)
Jeff LeJeune (Committee Member)
186 p.

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Citations

  • Abley, M. J. (2011). Tracking, Quantifying, Phenotyping and Genotyping of Campylobacter in Cattle and Pigs across the Farm to Fork Continuum [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306427015

    APA Style (7th edition)

  • Abley, Melanie. Tracking, Quantifying, Phenotyping and Genotyping of Campylobacter in Cattle and Pigs across the Farm to Fork Continuum. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1306427015.

    MLA Style (8th edition)

  • Abley, Melanie. "Tracking, Quantifying, Phenotyping and Genotyping of Campylobacter in Cattle and Pigs across the Farm to Fork Continuum." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306427015

    Chicago Manual of Style (17th edition)