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Journal of Clinical Microbiology, November 2005, p. 5705-5714, Vol. 43, No. 11
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.11.5705-5714.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Campylobacter coli in Swine Production: Antimicrobial Resistance Mechanisms and Molecular Epidemiology

Siddhartha Thakur and Wondwossen A. Gebreyes^*

Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, North Carolina 27606

Received 18 May 2005/ Returned for modification 5 July 2005/ Accepted 15 August 2005

The aim of this study was to determine antimicrobial resistance, to evaluate and compare the use of two genotyping methods for molecular epidemiology purposes, and to determine the genotypic diversity of Campylobacter coli of porcine origin. A total of 100 C. coli isolates from swine were tested for susceptibility to six antimicrobials using the agar dilution method and genotyped using two high-resolution fingerprinting approaches: multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Evaluation of the methods was based on their resistance patterns, discriminatory indexes (DI), high test throughputs, costs, and turnaround times. Resistance to erythromycin and tetracycline was the most common. Both genotypic methods were found to have high discriminatory power, although MLST had a higher DI (0.936) than PFGE (DI = 0.889). It also had a higher throughput than PFGE. Isolates were clustered into 27 groups by MLST compared to 11 by PFGE. MLST was able to further discriminate the isolates grouped under the same cluster by PFGE. Out of the 65 MLST sequence types (STs) identified among the total isolates, 50 were reported for the first time. Most STs were found to be specific to the farm (n = 38) and to slaughter (n = 22). Resistance against tetracycline and erythromycin was encoded by the tet(O) gene and a A2075G point mutation in the 23S rRNA gene, respectively. A high ciprofloxacin MIC (>64 µg/liter) was conferred by a point mutation in the gyrA gene. The weak clonal structure of the C. coli population among swine was further highlighted by the index of association value of 0.293. The findings of this study indicate that multidrug-resistant diverse C. coli strains exhibiting resistance to ciprofloxacin and erythromycin are concerning, since these are the drugs of choice for treating invasive campylobacteriosis cases in humans.

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* Corresponding author. Mailing address: Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, NC 27606. Phone: (919) 513-8291. Fax: (919) 515-3044. E-mail: wagebrey{at}ncsu.edu.

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Journal of Clinical Microbiology, November 2005, p. 5705-5714, Vol. 43, No. 11
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.11.5705-5714.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Thakur, S., Morrow, W. E. M., Funk, J. A., Bahnson, P. B., Gebreyes, W. A. (2008). Molecular Epidemiologic Investigation of Campylobacter coli in Swine Production Systems, Using Multilocus Sequence Typing. Appl. Environ. Microbiol. 74: 342-342 [Full Text]