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Molecular Epidemiology Of Campylobacter And Yersinia Enterocolitica Isolates From Pigs Reared In Conventional And Antibiotic Free Farms From Different Geographic Regions

Tadesse, Daniel Alemayehu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1230936664

Abstract Details

2009, Doctor of Philosophy, Ohio State University, Veterinary Preventive Medicine.
This dissertation is composed of four studies conducted in two predominant bacterial pathogens; Campylobacter spp. and Yersinia enterocolitica in swine production systems. The main scope was molecular epidemiology and antimicrobial resistance. The first study was conducted to determine the prevalence and antimicrobial resistance profile of Campylobacter in two regions. A total of 838 fecal and 1173 carcass samples were examined. Campylobacter isolation was done following recommended protocol. The minimum inhibitory concentration was determined using agar dilution to a panel of six antimicrobials. The overall Campylobacter prevalence was 56.3%. We found Campylobacter prevalence of 58.9% and 53.7% among conventional and antimicrobial free farms respectively (p=0.24). There was no significant difference between region 1 (54.1%) and region 2 (58.2%) (p=0.92). Higher proportions of Campylobacter were resistant to tetracycline (64.5%) and erythromycin (47.9%). Resistance to chloramphenicol (4.4%), gentamicin (3.2%), nalidixic acid (23.5%) and ciprofloxacin (4.9%) were also detected. Thirty-seven out of 1257 Campylobacter coli (2.9%) were resistant to both erythromycin and ciprofloxacin, drugs of choice for human campylobacteriosis. High prevalence of Campylobacter coli and high proportion of resistance in both conventional and ABF systems, regardless of antimicrobial use status, was found. We also evaluated the contribution of point mutations in the quinolone resistance determining region (QRDR) of the gyrA gene to quinolone resistance. A total of eighty Campylobacter isolates were selected based on minimum inhibitory concentration (MIC) of ciprofloxacin and nalidixic acid. Of the 21 ciprofloxacin and nalidixic acid resistant C. coli isolates, only six showed point mutations that resulted in Thr-86 to Ile (ACT to ATT) amino acid substitutions. These isolates had MICs > 4 μg/ml for ciprofloxacin and ≥ 128 μg/ml for nalidixic acid. No detectable gyrA mutation was detected among C. coli isolates with MIC ≤ 4 μg/ml to ciprofloxacin. The genotypic diversity of 99 C. coli isolates from different geographic regions, production systems and with different resistance patterns was also investigated by multilocus sequence typing method. A total of 50 different sequence types (ST), among which seven new ones, were identified. All STs belonged to ST-828 clonal complex with ST-828 putative founder ST. The most common ST was ST-854 (n=10) followed by ST-828 (n=5), ST-1096 (n=5) and ST-1100 (n=5). The C. coli population showed weak clonal structure with an IA of 0.46. Swine are recognized as a major reservoir and potential source of pathogenic Yersinia enterocolitica strains to humans. A total of 172 Y. enterocolitica were investigated to determine their pathogenic significance to humans. Phenotypic and genotypic diversity of the isolates were assessed using antibiogram, serogrouping and amplified fragment length polymorphism. Carriage of chromosomal and plasmid-borne virulence genes were investigated using PCR. More than two-thirds of Y. enterocolitica were pan-susceptible. The most predominant serotype was O:3 (43%). Twenty-two of 172 (12.8%) isolates were found to carry Yersinia adhesion A (yadA). Ail, ystA and ystB gene were detected in 36%, 77% and 26.2% of the strains, respectively. AFLP genotyping of isolates showed wide diversity and were grouped into nine clades.
Wondwossen Gebreyes (Advisor)
Fred DeGraves (Committee Member)
Paivi Rajala-Schultz (Committee Member)
Thomas Wittum (Committee Member)

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Citations

  • Tadesse, D. A. (2009). Molecular Epidemiology Of Campylobacter And Yersinia Enterocolitica Isolates From Pigs Reared In Conventional And Antibiotic Free Farms From Different Geographic Regions [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1230936664

    APA Style (7th edition)

  • Tadesse, Daniel. Molecular Epidemiology Of Campylobacter And Yersinia Enterocolitica Isolates From Pigs Reared In Conventional And Antibiotic Free Farms From Different Geographic Regions. 2009. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1230936664.

    MLA Style (8th edition)

  • Tadesse, Daniel. "Molecular Epidemiology Of Campylobacter And Yersinia Enterocolitica Isolates From Pigs Reared In Conventional And Antibiotic Free Farms From Different Geographic Regions." Doctoral dissertation, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1230936664

    Chicago Manual of Style (17th edition)

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