Campylobacter in Poultry: Physiology, genetics, and detection methods

Campylobacter from poultry production continues to be a prominent source of foodborne disease on a global scale. Despite this prominence and interest in controlling it in poultry, Campylobacter species such as Campylobacter jejuni and Campylobacter coli as well as other species belonging to the genus are still not well understood both in terms of biology, physiology, ecology or their dissemination in food production systems. This lack of understanding impacts not only the ability to control it but also understanding the epidemiology of how they contaminate poultry products such as poultry meat. Campylobacter exhibits several properties such as a viable nonculturable physiological state that can make it more difficult to not only detect but understand the role this phase may play in its survival in the environments associated with poultry production and poultry processing systems. Several culture-based enrichment and selective plating approaches are currently in use for the isolation and enumeration of Campylobacter from poultry matrices. However, these approaches can be labor intensive and are not always completely accurate thus complicating estimations in poultry production, particularly from the gut contents of live birds. As molecular advances have been made, polymerase chain reaction (PCR) assays have become readily available to achieve more rapid detection and in some cases improved sensitivity. In addition, whole genome sequencing has enabled more specific genetic typing of individual strains within species to greatly aid tracking of isolates during outbreaks and identify points of origin for the respective outbreaks associated with poultry. Finally, whole genome sequencing along with transcriptomics and proteomics have greatly enhanced understanding of fundamental genetic regulatory responses of Campylobacter during growth and colonization of poultry.

While Campylobacter contamination in poultry continues to be problematic, the prevalence in the chicken gastrointestinal tract has been an ongoing highly difficult issue to understand due to the complex relationship of Campylobacter with the indigenous cecal microbiota. It appears that Campylobacter may in fact be fairly intertwined with the rest of the cecal microbiota to the point of being almost inseparable. It is not clear what the relationships might be but this complexity certainly makes it difficult to design control measures that will be effective in the chicken gut. Several feed amendment approaches including botanicals, essential oils, and organic acids, have been explored but represent fairly broad spectrum antimicrobials that potentially could be generally disruptive to the overall cecal microbiota. While prebiotics and probiotics have proven to be effective against pathogens such as Salmonella in chickens, the results are less clear for Campylobacter probably in part due to its complex relationship with the native cecal microbiota. More specific treatments such as Campylobacter bacteriophage hold promise but efficacy remains to be optimized. Likewise developing Campylobacter vaccines using vaccine carrier vectors such as Salmonella to express Campylobacter epitopes have shown some promise. Future control strategies against Campylobacter in chickens will most certainly require a much better comprehension of the gut microbiome and the interactions occurring when colonized by Campylobacter.

This Research Topic aims to provide a comprehensive set of papers covering all aspects of Campylobacter specifically occurring in poultry and will encourage submissions on culture media developments, molecular detection, farm management, vaccine strategies, avian microbiome interactions, among other topics with an emphasis exclusively on poultry production. Methods, original research and reviews are all welcome.