Prevalence and Dissemination of Antimicrobial Resistance among Campylobacter jejuni and Campylobacter coli from Meat-Animals

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Title: Prevalence and Dissemination of Antimicrobial Resistance among Campylobacter jejuni and Campylobacter coli from Meat-Animals
Author: Islam, Mohammed Shahidul
Advisors: Jonathan Olson, Committee Member
Jonathan C. Allen, Committee Member
Sophia Kathariou, Committee Chair
Abstract: Campylobacter jejuni and C. coli from conventionally grown turkeys have been frequently reported to be resistant to nalidixic acid and ciprofloxacin. To reduce possible contributions of fluoroquinolone use in poultry production to fluoroquinolone resistance in poultry-derived Campylobacter, use of the fluoroquinolone enrofloxacin (trade name, Baytril) was banned in July 2005. However, the impact of this ban on fluoroquinolone resistance in thermophilic campylobacters from turkeys has not been rigorously evaluated yet. In this study, we investigated prevalence of quinolone/fluoroquinolone resistance and multidrug resistance among 1552 Campylobacter isolates (81% C. coli and 19% C. jejuni) derived from 2371 cecal samples of young turkeys (10 days to six weeks of age). The isolates were derived from different flocks and farms, representing three different integrators, from 2002 to 2008. Resistance to ciprofloxacin and nalidixic acid was highly prevalent (585/722, 81%) among isolates from 2002 to August 2005, and prevalence was even higher (779/830, 94%) among isolates from 2006 to 2008, the three surveyed years subsequent to the ban (p<0.0001). Multidrug resistant C. coli (resistant to tetracycline, streptomycin, kanamycin, erythromycin, nalidixic acid and ciprofloxacin) and C. jejuni (resistant to all of the above except erythromycin) represented 46% and 66% of the campylobacters isolated in the periods prior to and subsequent to the enrofloxacin ban, respectively. Multidrug resistance prevalence increased significantly post-ban (p<0.0001) for both C. coli and C. jejuni. Ciprofloxacin MIC determinations suggested that there was no obvious difference in MIC distribution before and after the enrofloxacin ban. Our results suggest that there was no detectable decrease in prevalence of fluoroquinolone resistance among turkey-derived campylobacters within the surveyed three-year period following the enrofloxacin ban. Instead, and for reasons that remain unknown, prevalence values for fluoroquinolone resistance and for multidrug resistance were higher post-ban than pre-ban (p<0.0001). Continued surveys are needed to further evaluate the potential impact of the ban on resistance of campylobacters from turkeys to fluoroquinolones and other antibiotics. Even though fluorioquinolones are no longer permitted for use in poultry, several antimicrobials, for instance tetracycline, continue to be used extensively in conventional production. Naturally competent C. coli C. jejuni are able to acquire foreign DNA from different sources through transformation but the role of transformation in the dissemination of tetracycline resistance in Campylobacter has not been investigated. We therefore investigated transfer of tetracycline resistance from tetracycline resistant C. coli and C. jejuni to tetracycline-susceptible (TS) C. coli and C. jejuni derived from meat animals. Tetracycline-resistant (TR) but kanamycin susceptible (KS) C. coli both from turkey and swine could serve as donors in transformation-mediated transfer of tetracycline resistance to TS C. coli from turkeys. TR and kanamycin-resistant (KR) C. coli from turkeys were unable to serve as donors of tetracycline resistance whereas certain TR KR swine-derived strains successfully transformed tetracycline resistance. None of the TR KR C. jejuni strains could serve as donors and overall C. coli proved to be better donors in transforming tetracycline resistance than C. jejuni. However, a bovine TR KS C. jejuni donors strain was successful in transforming turkey-derived as well as bovine C. jejuni to tetracycline resistance. Further studies are needed to evaluate the impact of transformation in dissemination of tetracycline resistance among C. jejuni and C. coli from animal production systems.
Date: 2009-12-02
Degree: MS
Discipline: Food Science

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