• Proximity to other commercial turkey farms affects colonization onset, genotypes and antimicrobial resistance profiles of Campylobacter in turkeys: suggestive evidence from a paired-farm model.

Authors: Jeffrey Niedermeyer, Lynde Ring, William Miler, Seiche Genger, Christina Parr Lindsey, Jason Osborne, and Sophia Kathariou

Abstract: Campylobacter is a leading foodborne pathogen, and poultry products are major vehicles for human disease. However, determinants impacting Campylobacter colonization in poultry remain poorly understood, especially with turkeys. Here we used a paired-farm design to concurrently investigate Campylobacter colonization and strain types in two turkey breeds (Hybrid and Nicholas) at two farms in eastern North Carolina. One farm (TAU) was a university teaching unit at least 40 km from commercial turkey farms, while the other (SIB) was a commercial farm in an area with a high density of turkey farms. Day-old birds were obtained from the same breeder flock and hatchery and placed at TAU and SIB on the same day. Birds were marked to identify turkey breed and then co-mingled on each farm. TAU birds became colonized one week later than SIB and had lower initial Campylobacter levels in the cecum. Interestingly, Campylobacter genotypes and antimicrobial resistance profiles differed markedly between the farms. Most TAU isolates were resistant only to tetracycline, whereas multi-drug resistant isolates predominated at SIB. Multilocus sequence typing revealed that no Campylobacter genotypes were shared between TAU and SIB. A bovine-associated genotype (ST-1068) predominated in C. coli from TAU, while SIB isolates had genotypes commonly encountered in commercial turkey production in the region. One multidrug-resistant C. jejuni strain (ST-1839) showed significant association with Nicholas turkeys. The findings highlight the need to further characterize the impact of farm-specific factors and turkey genetics on antimicrobial resistance and genotypes of C. jejuni and C. coli that colonize turkeys.

IMPORTANCE. Colonization of poultry with Campylobacter at the farm level is complex, poorly understood, and critically linked to contamination of poultry products, known to constitute a leading risk factor for human campylobacteriosis. Here we investigated the use of a paired-farm design under standard production conditions, and in the absence of experimental inoculations, to assess potential impacts of farm and host genetics on prevalence, antimicrobial resistance and genotypes of Campylobacter in commercial turkeys of two different breeds. Data suggest impacts of farm proximity to other commercial turkey farms on timing of colonization, genotypes and antimicrobial resistance profiles of Campylobacter colonizing the birds. Furthermore, the significant association of a specific multidrug-resistant C. jejuni strain with turkeys of one breed suggests colonization partnerships at the Campylobacter strain-turkey breed level. The study design avoids potential pitfalls associated with experimental inoculations, providing novel insights on the dynamics of turkey colonization with Campylobacter in actual farm ecosystems.

Niedermeyer JA, Ring L, Miller WG, Genger S, Parr Lindsey C, Osborne J, Kathariou S. 2018. Proximity to other commercial turkey farms affects colonization onset, genotypes and antimicrobial resistance profiles of Campylobacter in turkeys: suggestive evidence from a paired-farm model. Appl Environ Microbiol AEM.01212-18.


  • The Current State of Macrolide Resistance in Campylobacter: A Review of Trends and Impacts of Resistance Mechanisms (accepted in Applied and Environmental Microbiology 14 April 2017)

Authors: Hannah Bolinger and Sophia Kathariou

Abstract: Campylobacter spp., especially Campylobacter jejuni and C. coli, are leading bacterial foodborne pathogens worldwide. In the United States, an estimated 0.8 million cases of campylobacteriosis occur annually, mostly involving C. jejuni. Campylobacteriosis is generally self-limiting but in severe cases treatment with antibiotics may be mandated. Increasing incidence of fluoroquinolone resistance in Campylobacter has rendered macrolides like erythromycin and azithromycin the drugs of choice for human campylobacteriosis. Prevalence of macrolide resistance in C. jejuni remains low, but can be common in C. coli. Substitutions in the 23S rRNA gene, specifically A2075G, and less frequently A2074C/G, remain the most common mechanism for high-level resistance to macrolides. In C. jejuni, resistance mediated by such substitutions is accompanied by reduced ability to colonize chickens and other fitness costs, potentially contributing to the low incidence of macrolide resistance. Interestingly, similar fitness impacts have not been noted in C. coli. Also noteworthy is a novel mechanism first reported in 2014 in C. coli from China and mediated by erm(B) harbored on multidrug-resistance genomic islands. Incidence of erm(B) appears to reflect clonal expansion of certain strains and whole-genome sequencing has been critical to the elucidation of erm(B)-associated macrolide resistance in Campylobacter spp. Except for one report from Spain, erm(B)-mediated macrolide resistance has been restricted to Campylobacter, mostly C. coli, of animal and human origin from China. If erm(B)-mediated macrolide resistance does not confer fitness costs in C. jejuni the range of this gene may expand in C. jejuni, threatening to compromise treatment effectiveness of severe campylobacteriosis cases.

Bolinger, H.K., Kathariou, S. (2017) The Current State of Macrolide Resistance in Campylobacter: A Review of Trends and Impacts of Resistance Mechanisms. Applied and Environmental Microbiology doi:10.1128/AEM.00416-17

  • Reducing Campylobacter; A look at turkey industry management practices

Authors: Hannah K. Bolinger, Donna Carver, Sophia Kathariou


  • Investigation of Erythromycin-Resistant Campylobacter jejuni from Turkey Farms in North Carolina

Authors:  Hannah K. Bolinger, Margaret Kirchner, Kshipra Chandrashekhar, Jeff A. Niedermeyer, Donna K. Carver, Sophia Kathariou.

Presented by Margaret Kirchner as a poster at IAFP 2016 in St. Louis, MO

Introduction: Campylobacter is a leading cause of bacterial foodborne illness and is often linked to contaminated poultry. Macrolides such as erythromycin are the drugs of choice when treatment is indicated.  Even though erythromycin resistance is frequent among Campylobacter coli, it remains rare in Campylobacter jejuni and was not encountered during several years of surveillance of Campylobacter from turkeys in North Carolina.  However, from 2014-2016, three North Carolina turkey flocks were found to be colonized by erythromycin-resistant (ErmR) C. jejuni strains.

Purpose: The purpose of this study was to determine the prevalence of ErmR C. jejuni in turkey farms and identify the genetic cause of the resistance.

Results: ErmR C. jejuni was identified in 0.53%, 0.91%, and 2.0% (since 4/6/16) of the flocks from 2014-2016, respectively.  Of the three flocks with ErmR C. jejuni, one yielded isolates with ST-1839 and another ST-7729, which was novel and differed in all seven alleles from ST-1839. Previously identified ST-1839 isolates were multidrug-resistant but were erythromycin sensitive.  The ErmR C. jejuni isolates harbored the 23S rRNA mutation associated with macrolide resistance.  Resistance was found to be transferable by transformation and MICs comparable to that of the ErmR C. jejuni isolated for 2014-2016 turkey flocks.

Significance: Although uncommon in turkey flocks, flocks colonized by ErmR C. jejuni were identified.  The presence of a macrolide resistance associated mutation in a chromosomal locus suggests the potential for dissemination to other C. jejuni via transformation. These data will enhance the currently limited knowledge regarding ErmR C. jejuni in food animals and will contribute to further surveillance on the prevalence of ErmR C. jejuni in poultry.

  • Characterization of Campylobacter spp. from flies sourced from conventional turkey farms 

Authors:  Hannah K. Bolinger, Jeff A. Niedermeyer, Kenneth M. Mann, Donna K. Carver, Sophia Kathariou.

Presented by Hannah Bolinger as a poster at IAFP 2015 in Portland, OR

Introduction: Campylobacter is a leading agent of foodborne disease with poultry as major vehicle for human infections. Risk factors for colonization of poultry flocks with Campylobacter remain poorly characterized but include poor biosecurity and insect vectors, primarily flies and darkling beetles.  Flies may play a vital role in introduction and dissemination of Campylobacter through a flock. However, limited information is available on the characteristics of Campylobacter from flies in poultry farms.

Purpose: The purpose of this study was to determine the prevalence, species, and antibiotic susceptibility profiles of Campylobacter isolated from turkey feces and flies from turkey farms. Additionally, the diversity and correlations between susceptibility profiles of fly and fecal isolates were investigated.

Methods: Visits were made to 31 conventional turkey flocks.  At each visit, 12 fecal samples and 10 flies were collected. Campylobacter was isolated and enumerated on selective media (mCCDA), speciated (C. jejuni vs. C. coli) by multiplex PCR and characterized for susceptibility to a panel of antibiotics.

Results: The majority (92.3 %) of flocks were positive for Campylobacter both in fecal and fly samples. Most antimicrobial susceptibility profiles of isolates from feces were represented among those from flies.  However, isolates from flies tended to exhibit greater diversity of antimicrobial susceptibility profiles than those from feces- 2.36 different profiles/flock in flies vs. 2.04 in feces.

Significance:  The prevalence and diversity of Campylobacter spp. from turkeys and putative insect vectors, especially flies, remain poorly characterized. The findings suggest that  flies from turkey farms are commonly Campylobacter-positive and may exhibit a greater diversity of Campylobacter than suggested by analysis of isolates from feces.  The data will add to the body of literature on this subject and expand into the untapped area of the role of the fly in the spread of not just Campylobacter, but associated antibiotic resistances as well.


This article was initially published in the the North Carolina State University News site before being picked up by Food Safety News in April provides an overview of what Campylobacter is, what campylobacteriosis looks like, and how to best prevent this illness.


  • The Drugs and Bugs in Your Birds: Food Safety Implications of Antibiotic Resistance in Campylobacter

New Food Magazine, March 9, 2015,

This article discussed the ecology of Campylobacter and how it may be introduced into commercial poultry houses. Additionally, the historical and current state of antibiotic resistance in both C. jejuni and C. coli are discussed as well as possible public health and food safety concerns regarding antibiotic resistant Campylobacter.