Campus Units

Veterinary Microbiology and Preventive Medicine, Veterinary Diagnostic and Production Animal Medicine

Document Type


Publication Version

Accepted Manuscript

Publication Date


Journal or Book Title

Applied and Environmental Microbiology




Campylobacter is a major foodborne pathogen in humans and a significant cause of abortion in sheep. Although ruminants are increasingly recognized as important reservoirs for Campylobacter, limited information is available about the molecular epidemiology and antimicrobial resistance (AMR) profiles of sheep Campylobacter. Here we describe a two-trial study that examined Campylobacter profiles in sheep and determined whether in-feed tetracycline influenced the distribution and AMR profiles of Campylobacter. Each trial involved 80 commercial sheep naturally infected with Campylobacter, 40 of which were medicated with tetracycline in feed, while the other 40 received feed without antibiotics. Fecal and bile samples were collected for the isolation of Campylobacter. The bacterial isolates were analyzed for antimicrobial susceptibility and genotypes. The results revealed that 87.0% and 61.3% of the fecal and bile samples were positive for Campylobacter (C. jejuni and C. coli), with no significant differences between the medicated and non-medicated groups. All but one of the tested Campylobacter isolates were resistant to tetracycline. Although fluoroquinolone (FQ) resistance remained low in C. jejuni (1.7%), 95.0% of the C. coli isolates were resistant to FQ. Genotyping revealed that C. jejuni ST2862 and C. coli ST902 were the predominant genotypes in the sheep. Feed medication with tetracycline did not affect the overall prevalence, species distribution and AMR profiles of Campylobacter, but increased the total Campylobacter counts in bile and gallbladder. These findings identify predominant Campylobacter clones, reveal the high prevalence of FQ-resistant C. coli, and provide new insights into the epidemiology of Campylobacter in sheep.


This is a manuscript of an article published as Xia, Jing, Jinji Pang, Yizhi Tang, Zuowei Wu, Lei Dai, Kritika Singh, Changyun Xu, Brandon Ruddell, Amanda Kreuder, Lining Xia, Xiaoping Ma, Kelly S. Brooks, Melda M. Ocal, Orhan Sahin, Paul J. Plummer, Ronald W. Griffith, and Qijing Zhang. "High prevalence of fluoroquinolone-resistant Campylobacter in sheep and increased Campylobacter counts in the bile and gallbladder of sheep medicated with tetracycline in feed." Applied and Environmental Microbiology (2019). DOI: 10.1128/AEM.00008-19. Posted with permission.

Copyright Owner

American Society for Microbiology



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Published Version