Influence of Commercial Laying Hen Housing Systems on the Prevalence and Antimicrobial Resistance of Campylobacter from Laying Hens and Eggs

Estefanía Novoa Rama, Purdue University


Antibiotic-resistant Campylobacter is considered a severe threat to public health worldwide and in the United States alone, more than 300,000 annual infections with fluoroquinolone-resistant Campylobacter are estimated. The CDC reports that resistance to ciprofloxacin, an antibiotic used to treat severe Campylobacteriosis cases in adults, has been increasing over the past 20 years among bacteria of the Campylobacter genus isolated from both human and poultry. The most common presentation of Campylobacteriosis is a self-limited gastrointestinal disease characterized by diarrhea, fever and abdominal cramps. Serious sequelae of Campylobacter infections include the neurological disease known as Guillain-Barré syndrome (GBS), with an incidence rate of 1 in 1000 infections. The economic burden of GBS in the US amounts to $950 million per year, more than half of the total cost of Campylobacter-related illnesses. It is estimated that 50–70% of Campylobacteriosis incidences are linked to poultry and poultry production environments. In laying hens, high levels of Campylobacter prevalence in the gastrointestinal tract and reproductive organs have been reported, raising concerns with microbiological safety of eggs. Studies have reported low levels of eggshell contamination with Campylobacter. However, with eggs constituting one of the largest consumed food products in most countries, it is imminent to emphasize the need for effective pathogen control strategies in egg production. Furthermore, social and political discussions about laying hen housing for commercial egg production continue to arise worldwide due to global concerns with animal welfare and impacts on product safety. As a result, non-conventional housing systems, such as cage free and free range housing, have been developed. This study was conducted under the North Carolina Layer Performance and Management Test Program, over the course of a 10-month production period. A total of 355 environmental swabs and eggshell pools were collected every 8 weeks across 5 different hen housing types. Serological, biochemical, and molecular identification tests were performed to assess the prevalence of Campylobacter spp. in hens from the different housing systems. Additionally, genetic variability of the Campylobacter isolates was carried out using Pulsed-field Gel Electrophoresis (PFGE). Antimicrobial resistance of the Campylobacter isolates was also evaluated, using the micro-broth dilution method developed by the National Antimicrobial Resistance Monitoring System (NARMS). Through several real-time PCR assays, 20% of isolates were confirmed as Campylobacter spp., with 91.7% of such being identified as C. jejuni and 8.3% as C. coli. The overall Campylobacter prevalence was highest among samples taken from conventional cages (23.21%) while the lowest was observed in enrichable cages (13.33%). Differences however were not statistically significant, thus no correlation (P>0.05) between Campylobacter prevalence and housing types was observed. Campylobacter spp. isolates exhibited resistance most frequently to tetracycline (60%) followed by resistance to nalidixic acid (1.4%); both important antimicrobials for human medicine. Finally, the fingerprinting of Campylobacter by PFGE resulted in 23 different types with one leading PFGE type comprising over 40% of isolates. Findings from this study are concerning, and illustrate the need for the development of appropriate interventions to prevent the spread of antimicrobial-resistant Campylobacter among laying hens and eggs.




Oliver, Purdue University.

Subject Area

Food Science|Microbiology|Animal sciences

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